Method and apparatus for applying discontinuous reception mode in wireless communication system

ABSTRACT

The disclosure relates to a 5G or pre-5G communication system. A method performed by a terminal, includes receiving, from a BS, first system information including first information for an extended DRX mode; receiving, from a BS, second system information including second information associated with a DRX cycle; determining whether to request activation of the extended DRX mode based on the first information; when it is determined to request the activation of the extended DRX mode, transmitting, to an MME, a request message including third information for an operation in the extended DRX mode; receiving, from the MME, a response message based on the request message; when the response message includes fourth information for the operation in the extended DRX mode, performing the operation in the extended DRX mode based on the second information and the fourth information; and when the response message does not include the fourth information, performing an operation in a regular DRX mode based on the second information.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/751,079, which was filed in the U.S. Patent and Trademark Office(USPTO) on Feb. 7, 2018, which is a National Phase Entry of PCTInternational Application No. PCT/KR2016/008705, which was filed on Aug.8, 2016, and claims priority to U.S. Provisional Patent Application No.62/202,416, which was filed in the USPTO on Aug. 7, 2015, the entirecontent of each of which is incorporated herein by reference.

BACKGROUND 1. Field

The present invention relates to a mobile communication system and, moreparticularly, to a method and apparatus for applying a discontinuousreception mode in a wireless communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud Radio Access Networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,Coordinated Multi-Points (CoMP), reception-end interference cancellationand the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology. Accordingly, variousattempts are now made to apply the 5G communication system to the IoTnetwork. For example, technologies such as a sensor network,machine-to-machine (M2M), and machine type communication (MTC) areimplemented by techniques such as beamforming, MIMO, and array antennaswhich belong to the 5G communication technology. To apply a cloud radioaccess network (cloud RAN) for the above-mentioned big data processingtechnology is an example of the fusion of the 5G technology and the IoTtechnology.

In general, wireless communication systems have been developed for thepurpose of providing communication while maintaining user's mobility.Recently, the wireless communication technology has achieved asignificant growth, and also the communication system technology issteadily evolving. With the rapid progress of such technologies, thewireless communication system has reached the stage of providing ahigh-speed data communication service as well as voice communication. Inrecent years, the next generation mobile communication system isevolving from human-to-human (H2H) communication into human-to-machine(H2M) communication and machine-to-machine (M2M) communication.

On the other hand, as a terminal becomes more sophisticated, there is aneed of a method for reducing the power consumption of the terminal inorder to improve battery performance. To reduce power consumption, theterminal may operate in a discontinuous reception (DRX) mode. Theterminal may perform a reception operation to receive a paging signalfrom a base station. However, since the paging signal is not transmittedfrequently, the power loss becomes large if the terminal performs thereception operation even during no arrival of the paging signal.Therefore, in order to reduce power consumption, the reception operationfor receiving the paging signal may be periodically performed onlyduring a specific time period. This is referred to as DRX.

Further, a method for increasing a DRX cycle to improve powerconsumption is being discussed. This is referred to as extended DRX(eDRX). However, some terminal, some base station, and some mobilitymanagement entity (MME) may not support the eDRX. Therefore, a methodfor operating in the eDRX mode by identifying whether such entitiessupport the eDRX is needed.

In addition, the base station may notify a change of system informationto the terminal through a paging message. However, when the extended DRXis applied, there may be a case incapable of receiving the pagingmessage, and the terminal may fail to know whether the systeminformation is changed. Therefore, the terminal needs a method foridentifying whether the system information is changed.

SUMMARY

In order to solve the above problems, the present invention provides amethod for a terminal to apply the eDRX after identifying whether a basestation and an MME support the eDRX.

In addition, when the eDRX is applied, the present invention provides amethod for a terminal to identify whether system information is changed,and to receive the changed system information.

According to an aspect of the disclosure, a method of a terminal isprovided, which includes receiving, from a base station, first systeminformation including first information for an extended DRX mode;receiving, from a base station, second system information includingsecond information associated with a DRX cycle; determining whether torequest activation of the extended DRX mode based on the firstinformation; in case that it is determined to request the activation ofthe extended DRX mode, transmitting, to an MME, a request messageincluding third information for an operation in the extended DRX mode;

receiving, from the MME, a response message based on the requestmessage; in case that the response message includes fourth informationfor the operation in the extended DRX mode, performing the operation inthe extended DRX mode based on the second information and the fourthinformation; and in case that the response message does not include thefourth information for the operation in the extended DRX mode,performing an operation in a regular DRX mode based on the secondinformation.

According to the present invention, the terminal can reduce powerconsumption thereof by identifying whether the base station and the MMEsupport the eDRX and then by applying the eDRX.

In addition, according to the present invention, even when the eDRX isapplied, the terminal can efficiently perform the eDRX operation byidentifying whether the system information is changed, and by receivingthe changed system information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram illustrating a communication scenario according tothe present invention;

FIG. 2 is a diagram illustrating paging occasions in the first DRX;

FIG. 3 is another diagram illustrating paging occasions according to thepresent invention;

FIG. 4 is a diagram illustrating a process of determining a first DRXcycle by UE;

FIG. 5 is a diagram illustrating a process of determining a second DRXcycle by UE according to a first method of a first embodiment of thepresent invention;

FIG. 6 is a diagram illustrating a UE operation according to the firstmethod of the first embodiment of the present invention;

FIG. 7 is a diagram illustrating an eNB operation according to the firstmethod of the first embodiment of the present invention;

FIG. 8 is a diagram illustrating an MME operation according to the firstmethod of the first embodiment of the present invention;

FIG. 9 is a diagram illustrating a process of determining a second DRXcycle by UE according to a second method of the first embodiment of thepresent invention;

FIG. 10 is a diagram illustrating a UE operation according to the secondmethod of the first embodiment of the present invention;

FIG. 11 is a diagram illustrating an eNB operation according to thesecond method of the first embodiment of the present invention;

FIG. 12 is a diagram illustrating an MME operation according to thesecond method of the second embodiment of the present invention;

FIG. 13 illustrates a configuration of UE according to the presentinvention;

FIG. 14A illustrates a block configuration of eNB according to thepresent invention;

FIG. 14B is a diagram illustrating a configuration of an MME accordingto an embodiment of the present invention;

FIG. 15 is a diagram illustrating a process of changing systeminformation;

FIG. 16A is a diagram illustrating a method for notifying changed systeminformation to UE according to a second embodiment of the presentinvention;

FIG. 16B is a diagram illustrating a modification period according tothe second embodiment of the present invention;

FIG. 17 is a diagram illustrating a UE operation according to the secondembodiment of the present invention;

FIG. 18A is a diagram illustrating an eNB operation in the presentinvention;

FIG. 18B is a diagram illustrating another eNB operation in the presentinvention;

FIG. 19 illustrates a block configuration of UE according to the presentinvention;

FIG. 20 is a diagram illustrating a configuration of eNB according tothe present invention;

FIG. 21 is a diagram illustrating a method for notifying changed systeminformation to UE according to a third embodiment of the presentinvention;

FIG. 22 is a diagram illustrating a UE operation according to the thirdembodiment of the present invention;

FIG. 23 is a diagram illustrating an eNB operation according to thethird embodiment of the present invention;

FIG. 24 illustrates a block configuration of UE according to the thirdembodiment of the present invention;

FIG. 25 illustrates a block configuration of eNB according to the thirdembodiment of the present invention;

FIG. 26 is a diagram illustrating a method for notifying changed systeminformation to UE according to a fourth embodiment of the presentinvention;

FIG. 27 is a diagram illustrating a UE operation according to the fourthembodiment of the present invention;

FIG. 28 is a diagram illustrating an eNB operation in the presentinvention;

FIG. 29 illustrates a block configuration of UE according to the presentinvention; and

FIG. 30 illustrates a block configuration of eNB according to thepresent invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

In the following description of embodiments, descriptions of techniquesthat are well known in the art and not directly related to the presentinvention are omitted. This is to clearly convey the gist of the presentinvention by omitting an unnecessary explanation.

For the same reason, some elements in the drawings are exaggerated,omitted, or schematically illustrated. Also, the size of each elementdoes not entirely reflect the actual size. In the drawings, the same orcorresponding elements are denoted by the same reference numerals.

In the following description of embodiments, descriptions of techniquesthat are well known in the art and not directly related to the presentinvention are omitted. This is to clearly convey the gist of the presentinvention by omitting an unnecessary explanation.

For the same reason, some elements in the drawings are exaggerated,omitted, or schematically illustrated. Also, the size of each elementdoes not entirely reflect the actual size. In the drawings, the same orcorresponding elements are denoted by the same reference numerals.

The advantages and features of the present invention and the manner ofachieving them will become apparent with reference to embodimentsdescribed in detail below with reference to the accompanying drawings.The present invention may, however, be embodied in many different formsand should not be construed as limited to embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art. To fully disclose the scope of theinvention to those skilled in the art, and the invention is only definedby the scope of claims.

It will be understood that each block of the flowchart illustrations,and combinations of blocks in the flowchart illustrations, may beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which are executed via the processor of the computer or otherprogrammable data processing apparatus, generate means for implementingthe functions specified in the flowchart block or blocks. These computerprogram instructions may also be stored in a computer usable orcomputer-readable memory that may direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process suchthat the instructions that are executed on the computer or otherprogrammable apparatus provide steps for implementing the functionsspecified in the flowchart block or blocks.

In addition, each block of the flowchart illustrations may represent amodule, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that in some alternativeimplementations, the functions noted in the blocks may occur out of theorder. For example, two blocks shown in succession may in fact beexecuted substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved.

The term “unit”, as used herein, may refer to a software or hardwarecomponent or device, such as a field programmable gate array (FPGA) orapplication specific integrated circuit (ASIC), which performs certaintasks. A unit may be configured to reside on an addressable storagemedium and configured to execute on one or more processors. Thus, amodule or unit may include, by way of example, components, such assoftware components, object-oriented software components, classcomponents and task components, processes, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuitry, data, databases, data structures, tables, arrays,and variables. The functionality provided for in the components andunits may be combined into fewer components and units or furtherseparated into additional components and modules. In addition, thecomponents and units may be implemented to operate one or more centralprocessing units (CPUs) in a device or a secure multimedia card.

FIG. 1 is a diagram illustrating a communication scenario according tothe present invention.

Referring to FIG. 1, communication devices 105 may be connected to awireless operator network 110.

For example, machine-type communication devices may be defined ingeneral as various unmanned devices such as meters or automatic vendingmachines, and have various features. Also, the machine-typecommunication devices may have different features depending on theirtypes.

In one cell, there may be very many communication devices having variousfeatures. A communication server 115 that has information about thecommunication devices may not only perform authentication, but alsocollect information from the communication devices and transmit thecollected information to a communication user 120. The communicationserver may exist within or outside the wireless operator network. Thecommunication user 120 may refer to an end-user who needs informationdelivered from the communication device. In this disclosure, forconvenience of explanation, a machine-type communication device thatperforms machine-to-machine communication will be described as anexample of the communication device. However, the scope of the presentinvention is not limited thereto. The communication device may include acommunication device that performs human-to-human communication, acommunication device that performs human-to-machine communication, andthe like. That is, the present invention may be applied to allcommunication devices that require the reduction of power consumption.

As mentioned above, machine-type communication has various differentfeatures. Also, such features may be classified into various typesaccording to the purposes of using the machine-type communication. Forexample, communication devices that require communication only a givennumber of times a day, regardless of time, have a time tolerant feature.In addition, machine-type communication devices installed in a certainplace and collecting specific information without mobility have a lowmobility feature. The wireless operator should provide services inconsideration of such various features of machine-type communication andcoexistence with existing terminals.

Among machine-type communication devices, devices related to trackinganimals, freight vehicles, etc. are generally supplied with power byusing a battery or autonomously generating electric power. Therefore,such machine-type communication devices should use limited power, sothat it is desirable to efficiently use limited power. Such amachine-type communication device has an extra low power consumptionmode and may be set to use low power in this mode.

As described above, one of ways to improve power consumption is toincrease a DRX cycle. In this disclosure, the DRX that operates in atypical cycle (hereinafter referred to as a first cycle or a first DRXcycle) may be referred to as first DRX, and the DRX that operates in anincreased cycle (hereinafter referred to as a second cycle or a secondDRX cycle) may be referred to as eDRX or second DRX. Accordingly, inthis disclosure, the first DRX may be defined as the DRX that operatesin the first cycle, and the second DRX may be defined as the DRX thatoperates in the second cycle. The second cycle may be longer than thefirst cycle.

In the LTE system, the first DRX operation of UEs placed in the idlestate may be performed through Equation 1 below. A system frame number(SFN) may be increased by one every radio frame. When a paging signal istransmitted in a radio frame that satisfies Equation 1, the UE mayperform a reception operation by the first DRX. Hereinafter, a radioframe in which a paging signal is transmitted may be referred to as apaging frame (PF). In addition, a subframe for transmitting a pagingsignal within a paging frame may be referred to as a paging occasion(PO).SFN mod T=(T div N)*(UE_ID mod N)  <Equation 1>

Where,

SFN: system frame number. This may be composed of 10 bits. (MSB 8 bitsexplicit, LBS 2 bits implicit)

T: first DRX cycle information of the UE. This may be transmitted on asystem information block 2 (SIB2). ENUMERATED {rf32, rf64, rf128, rf256}

N: min(T, nB)

Paging-related first parameter nB: This may be transmitted on SIB2.ENUMERATED {4T, 2T, T, T/2, T/4, T/8, T/16, T/32}

UE_ID: IMSI mod 1024 (IMSI may mean a unique number assigned to each UE)

Specifically, the SFN may be transmitted to the UE through a masterinformation block (MIB). In the MIB transmitted on the physicalbroadcast channel (PBCH), 8 bits may indicate the SFN.

The first DRX cycle information (T) and the paging-related firstparameter (nB) may be provided through the SIB. For example, the firstDRX cycle information (T) and the paging-related first parameter (nB)may be included in the SIB2 (SystemInformationBlockType2) and providedfrom eNB. The first DRX cycle information (T) may have one value fromamong {rf32, rf64, rf128, rf256}, where r32 may represent the length of32 radio frames. That is, r32 may mean 320 ms. In addition, thepaging-related first parameter (nB) may indicate the number of times ofpaging or the frequency of paging. In this disclosure, the first DRXcycle information (T) and the paging-related first parameter (nB),provided through the SIB, may be referred to as first DRX configurationinformation or first DRX parameters.

FIG. 2 is a diagram illustrating paging occasions in the first DRX.

Referring to FIG. 2, the SFN 205 may be increased by one every radioframe. In addition, the value of the SFN may be reset to zero in a 1024cycle 210.

Referring to Equation 1, the same pattern of paging 215 may be repeatedevery SFN cycle. From Equation 1, it can be seen that the maximum cycleof the first DRX is 2.56 seconds, and it can be seen that the first DRXcycle, even though being maximally increased, cannot exceed the SFNcycle, i.e., 10.24 seconds. In other words, if it is required toincrease the first DRX cycle more than 10.24 seconds for reduction ofpower consumption, the SFN cycle should be also increased.

Accordingly, in order to increase the SFN cycle, the present inventionmay include an additional SFN bit in a typical or new SIB and define UEoperation for receiving this. The SFN bit is increased by one every SFNcycle. The value indicated by the additional SFN bit may be referred toas a hyper SFN (HFN).

All the UEs do not need to receive the SIB including the additional SFNbit, and only the UE to which a very long DRX cycle is applied mayattempt reception. In addition, system information change relatedinformation (systemInfoValueTag value (one information (IE) included inthe SIB1)), which is increased by one every time of SIB informationchange, and a system information change indicator(systemInfoModification IE), which is included in paging and indicateswhether system information (SI) is changed, are not affected by a changeof the SFN bit value. That is, even if the SFN bit value is changed, theSI change related information (systemInfoValueTag IE) is not updated,and the SI change indicator (systeminfoModification IE) is nottransmitted through paging.

FIG. 3 is another diagram illustrating paging occasions according to thepresent invention.

As described above, the HFN may be increased by one every SFN cycle.That is, the HFN 305 may be composed of 1024 SFNs 310. Also, the SFN 310may be increased by one every radio frame. The eNB may generate paging320 by Equation 1 in the SFN cycle determined by Equation 2 to bedescribed below.

Specifically, assumed in the present invention is a method for receivinga paging signal several times during a predetermined DRX period in orderto increase the DRX cycle and also increase the probability of successin receiving the paging signal. For this, the paging occasion may bedetermined through a two-step process.

1) First step: Determine the SFN cycle (or HFN) in which the paging willoccur

2) Second step: Determine the radio frame in which the paging willoccur, in the SFN cycle (or HFN) determined at the first step

At the first step, the SFN cycle in which the paging will occur may bedetermined. The added SFN bits may have a value increased by one everySFN cycle. As described above, a value represented by the added SFN bitsmay be defined as a hyper system frame number (HFN).

Using Equation 2, the UE may identify the SFN cycle in which the pagingwill occur. In the present invention, the SFN cycle (or HFN) in whichthe paging will occur may be referred to as a paging hyper frame (PHF).HFN mod T′=(T div N)*(UE_ID mod N)  <Equation 2>

Where

N′: min(T′, nB′)

UE_ID: IMSI mod 1024 (or MTC device group ID mod 1024)

The second DRX cycle information (T′) and the paging-related secondparameter (nB′) may be provided from the eNB via the SIB. The second DRXcycle information (T′) and the paging-related second parameter (nB′) maybe included in the SIB2, as the first DRX cycle information (T) and thepaging-related first parameter (nB), or included in another SIB.

In the present invention, the second DRX cycle information (T′) and thepaging-related second parameter (nB′) provided through the SIB may bereferred to as second DRX configuration information or a second DRXparameter.

The UE identifier (UE_ID) may be derived by the same IMSI moduleoperation as in the normal UE. In case of a machine-type communicationdevice, the device may be represented in the form of a group ID, so thatthe group ID may be applied. After determining the PHF which is the SFNcycle in which the paging will occur, the UE may determine, in the SFNcycle, the specific radio frames in which the paging will occur. UsingEquation 1, the UE may identify the radio frame in which the paging willoccur in the SFN cycle.

If the paging occurrence occasion is defined in two steps as discussedabove and if the communication devices have the DRX cycle accordingly,the power consumption may be greatly reduced. In addition, since thepaging may repeatedly occur in the SFN cycle determined at the firststep according to setting of the first DRX cycle information (T) and thepaging-related first parameter (nB), the paging reception probabilitymay be increased.

Specifically, the UE that operates in the second DRX may perform the DRXoperation according to the first cycle during a specific period when thesecond cycle arrives. Herein, the specific period may be referred to asa paging time window (PTW). Like this, by allowing the paging to berepeatedly received during the specific period, the paging receptionprobability may be increased.

However, the second DRX having an increased cycle as described above mayhave a problem of whether it is supported by the UE, the eNB and theMME. Accordingly, proposed hereinafter is a method for determining theDRX cycle by identifying whether the entity supports the second DRX, andoperating in the DRX according to the determined cycle.

First Embodiment

FIG. 4 is a diagram illustrating a process of determining a first DRXcycle by UE.

The eNB 405 may transmit system information to the UE at step S410.Specifically, using the SIB2 which is one of system informationbroadcasted to the UE, the eNB 405 may provide the first DRX-relatedfirst information (e.g., a default DRX value) to the UE 400. In thepresent invention, the first DRX-related first information may refer tofirst DRX cycle information provided to the UE by the eNB.

The UE that receives the system information may transmit a requestmessage to the MME at step S420. In this case, the request message mayinclude, for example, an attach request message or a tracking areaupdate (TAU) message. The request message may be transmitted as anon-access stratum message to the MME via the eNB.

If the UE desires a shorter DRX cycle than the received firstDRX-related first information (the default DRX value), the UE maytransmit a desired DRX cycle to the MME through an ATTACH process. Thatis, the UE may include the first DRX-related second information (e.g., aUE specific DRX value) in the request message and transmit the requestmessage to the MME 410. In this case, the first DRX-related secondinformation (the UE specific DRX value) may include the first DRX cycleinformation desired by the UE.

Thereafter, if there is paging for the UE, the MME may transmit a pagingmessage to the eNB at step S430. At this time, the MME may transmit thefirst DRX-related second information (the UE specific DRX value),received from the UE, to the eNB together with the paging.

At step S440, the UE may determine the first DRX cycle by selecting asmaller value between the first DRX-related second information (the UEspecific DRX value) transmitted to the MME and the first DRX-relatedfirst information (the default DRX value) received from the eNB.

Also, at step S450, the eNB may determine the first DRX cycle byselecting a smaller value between the first DRX-related secondinformation (the UE specific DRX value) received from the MME and thefirst DRX-related first information (the default DRX value) beingbroadcasted by itself.

In this way, the UE and the eNB may select the same first DRX cycle, andthe eNB may determine a paging frame (PF), based on the first DRX cycle,and then transmit the paging to the UE.

Meanwhile, when the second DRX (eDRX) using an increased DRX cycle isapplied, the present invention proposes a method for determining whetherthe second DRX (eDRX) is supported by the UE, the eNB, and the MME. Afirst method independently considers whether the MME and the eNB supportthe second DRX (eDRX), and a second method considers only whether theeNB supports the second DRX (eDRX).

First Method

The first method is characterized in that the MME notifies the UEwhether the second DRX (eDRX) is supported, by using a response message(e.g., an ATTACH ACCEPT or TAU ACCEPT message) corresponding to therequest message received from the UE. Considering both whether the MMEsupports the second DRX (eDRX) and whether a serving cell supports thesecond DRX (eDRX), the UE may determine whether to apply the second DRX(eDRX).

FIG. 5 is a diagram illustrating a process of determining a second DRXcycle by UE according to a first method of a first embodiment of thepresent invention.

Referring to FIG. 5, the eNB may broadcast system information at stepS510. In case of supporting the second DRX (eDRX), the eNB 503 maybroadcast the system information including the second DRX-related firstinformation. For example, the eNB may provide SIB2 and SIBx. In thiscase, the SIB2 may include the first DRX-related first information (thetypical default DRX value), and the SIBx may include the secondDRX-related first information.

The second DRX-related first information may include information (anindicator) indicating whether the second DRX is supported, or a defaulteDRX value. The second DRX-related first information may be included ina typical SIB or a newly defined SIB. For example, the secondDRX-related first information may be included in SIB1.

At step S520, the UE may transmit a request message to the eNB. Usingthe request message (an ATTACH REQUEST or TAU REQUEST message), the UEmay transmit the first DRX-related second information (a UE specific DRXvalue) and the second DRX-related second information (a UE specific eDRXvalue) to the MME.

Specifically, if the eNB is broadcasting the first DRX-related firstinformation, and if the UE decides that it is necessary to apply thesecond DRX (eDRX), the UE may provide the second DRX-related secondinformation (e.g., a desired UE specific DRX value) to the MME 505. Atthis time, the second DRX-related second information may include thesecond DRX cycle information desired by the UE.

As described above, the first DRX-related second information may includecycle information desired by the UE for the first DRX, and the secondDRX-related second information may include cycle information desired bythe UE for the second DRX.

The reason that the UE transmits the first DRX-related secondinformation (the UE specific DRX value) to the MME even though desiringto apply the second DRX (eDRX) is that, if the MME does not support thesecond DRX (eDRX), the UE desires to apply the first DRX according tothe first DRX (the typical DRX) application procedure.

In addition, even when the second DRX (eDRX) is applied, the pagingframe (PF) and the paging occasion (PO) for actual transmission of thepaging within the hyper frame number (HFN) are determined according tothe first DRX configuration information (the typical DRX configurationinformation). Therefore, in order to derive the first DRX cycle (thetypical DRX value), the first DRX-related second information should beprovided to the MME.

Thereafter, at step S530, the MME may transmit a response messagecorresponding to the request message to the UE.

If the MME supports the second DRX (eDRX), the MME may transmit thesecond DRX-related third information to the UE by using a responsemessage (an ATTACH ACCEPT or TAU ACCEPT message).

The second DRX-related third information may include allowed second DRXcycle information, and the MME may provide the second DRX (eDRX) cycleinformation to the UE through the response message. Alternatively, byincluding the second DRX-related third information in the responsemessage, the MME may notify the UE that the MME supports the second DRX.

In the present invention, the second DRX cycle information transmittedby the MME may be referred to as allowed second DRX parameter (allowedeDRX parameter). The allowed second DRX (eDRX) cycle information may bethe same as or different from the second DRX-related second information(the UE specific eDRX value) provided to the MME by the UE through therequest message (the ATTACH REQUEST or TAU REQUEST message).

Alternatively, the second DRX-related third information may include anindicator indicating whether the second DRX is supported. This indicatormay be formed of 1-bit information. In case of simply providing whetherthe second DRX is supported, the second DRX-related third informationincluded in the response message may mean that the second DRX-relatedsecond information (the UE specific eDRX value) can be supported. Inthis case, the second DRX-related third information may be the same asthe second DRX-related second information.

The UE that receives the response message may determine the DRX cycle atstep S540.

If the second DRX-related third information is included in the responsemessage received from the MME, the UE may determine the second DRX cycleby using the second DRX-related third information. In this case, if thesecond DRX-related third information transmitted by the MME is identicalwith the second DRX-related second information transmitted by the UE,the UE may select the second DRX-related second information or thesecond DRX-related third information as the second DRX cycle.

On the other hand, if the second DRX-related third information and thesecond DRX-related second information are different from each other, theUE may select the second DRX-related third information as the second DRXcycle.

In addition, If the UE receives the second DRX-related third informationfrom the MME and thereby confirms that the MME supports the second DRX(eDRX), the UE may determine the first DRX cycle (T) by selecting asmaller value between the first DRX-related first information (thedefault DRX value) and the first DRX-related second information (the UEspecific DRX).

Alternatively, in order to determine the second DRX cycle, the UE maydetermine the second DRX (eDRX) cycle (T′) by selecting a smaller orlarger value between the second DRX-related first information value andthe second DRX-related second information (the UE specific eDRX).

If it is determined that the MME does not support the second DRX (eDRX),the UE may determine the DRX cycle (T) by selecting a smaller valuebetween the first DRX-related first information (the default DRX value)and the first DRX-related second information (the UE specific DRX).

Meanwhile, the MME that transmits the response message may transmitpaging to the eNB at step S550. At this time, the MME may transmit thefirst DRX-related second information (the UE specific DRX) and thesecond DRX-related third information to the eNB together with the pagingfor the UE.

However, if the MME does not support the second DRX (eDRX), only thefirst DRX-related second information (the UE specific DRX) may beprovided to the eNB together with the paging as in a typical case.

Accordingly, the eNB may determine the DRX cycle at step S560. Uponconfirming that the MME supports the second DRX (eDRX), the eNB maydetermine the second DRX cycle by using the second DRX-related thirdinformation transmitted by the MME. Also, the eNB may determine the DRXcycle (T) by selecting a shorter value between the first DRX-relatedfirst information (the default DRX value) and the first DRX-relatedsecond information (the UE specific DRX) received from the MME.

Alternatively, with respect to the second DRX cycle, the eNB maydetermine the second DRX (eDRX) cycle (T′) by selecting a smaller orlarger value between the second DRX-related first information and thesecond DRX-related third information (the allowed eDRX parameter)received from the MME.

Accordingly, using the determined second DRX cycle and the first DRXcycle, the UE may perform the DRX operation.

Meanwhile, the UE may move and, after performing cell reselection, campon a new serving cell. The UE may acquire system information broadcastedby the serving cell, for example, the first DRX-related firstinformation (the default DRX cycle) and the paging-related firstparameter (the nB value) from the SIB 2, and the second DRX-relatedfirst information and the paging-related second parameter (the nB′value) from the SIB x. At this time, if the following two conditions aresatisfied, the UE determines to apply the second DRX (eDRX).

(1) The second DRX-related third information (the allowed UE eDRXparameter) is received from the MME in the current tracking area (TA).

(2) The second DRX-related first information (or the second DRX (eDRX)parameter) is included in the system information of the current servingcell.

On the other hand, if either of the following conditions is satisfied,the UE does not apply the second DRX (eDRX).

(1) The second DRX-related third information (the allowed UE eDRXparameter) is not received from the MME in the current TA.

(2) Although the second DRX-related third information (the allowed UEeDRX parameter) is received from the MME in the current TA, the UE doesnot include the second DRX-related first information (or the second DRX(eDRX) parameter) in the system information of the current serving cell.

If the UE determines to apply the second DRX (eDRX), the UE may selectthe second DRX-related third information received from the MME as thesecond DRX cycle. Alternatively, the UE may determine the second DRXcycle (T′) by selecting a smaller or larger value between the secondDRX-related first information and the second DRX-related secondinformation (Min (or Max) [default eDRX, UE eDRX]).

In addition, the UE may determine the first DRX cycle (T) by selecting asmaller value between the first DRX-related first information and thefirst DRX-related second information (Min [default DRX, UE DRX]).Therefore, the UE may determine the PHF by using the second DRX cycle(T′) and determine the PF by using the first DRX cycle (T). As describedabove, the UE does not perform paging monitoring in the hyper frame (HF)which is not the PHF, and may perform the paging monitoring in the PF ofthe HF which is the PHF. The HF may refer to a frame indicated by theHFN.

If the UE determines to apply the first DRX (not to apply the secondDRX), the UE may determine the first DRX cycle (T) by selecting asmaller value between the first DRX-related first information and thefirst DRX-related second information (Min [default DRX, UE DRX]). Thesecond DRX cycle (T′) may be regarded as 1 (that is, all the HFs areregarded as the PHF), or the paging-related second parameter (nB′) maybe set as the second DRX cycle (T′) (likewise, all the HFs may beregarded as the PHF). Therefore, the UE may perform the pagingmonitoring in the PF of all the HFs.

Thereafter, the MME may receive incoming data from an S-GW. If thecurrent TA of target UE to which the incoming data is to be transmittedis TA x, if all serving cells of the TA x support the second DRX (eDRX),and if the MME transmits the second DRX-related third information (theallowed UE eDRX parameter) to the UE, the MME may generate a pagingmessage including the first DRX-related second information (the UE DRXcycle) and the second DRX-related third information (the allowed UE eDRXcycle) and transmit the generated paging message to the eNB.

If the serving cells of the TA x do not support the second DRX (eDRX),or if the MME does not transmit the second DRX-related third information(the allowed UE eDRX parameter), a paging message including the firstDRX-related second information (the UE DRX cycle) may be generated andtransmitted to the eNB.

In the present invention, the first DRX-related first information may bereferred to as a default DRX cycle, a default DRX value, or the like.Also, the first DRX-related second information may be referred to as aUE specific DRX value, a UE specific DRX cycle, a UE DRX cycle, a UEDRX, or the like. Similarly, the second DRX-related second informationmay be referred to as a UE specific eDRX value, a UE specific eDRXcycle, a UE eDRX cycle, a UE eDRX, or the like, and the secondDRX-related third information may be referred to as an allowed UE eDRXparameter, an allowed UE eDRX cycle, or the like. Although used namesare different, the contents included in each information may be thesame.

FIG. 6 is a diagram illustrating a UE operation according to the firstmethod of the first embodiment of the present invention.

Referring to FIG. 6, at step S610, the UE may be powered on, or thetracking area (TA) may be changed.

At step S620, the UE may acquire system information from the eNB.

At step S630, the UE that acquires the system information may identifywhether the system information includes the second DRX configurationinformation. That is, the UE may determine whether the systeminformation includes the second DRX-related first information and thepaging-related second parameter (the nB′ value).

If the system information includes the second DRX-related firstinformation and the paging-related second parameter (the nB′ value), theUE may perform an RRC connection establishment process at step S640.

After the RRC connection is completed, the UE may transmit a requestmessage at step S650. If the UE prefers to apply the second DRX (eDRX)or if the UE supports the second DRX, the UE may include the firstDRX-related second information (the UE specific DRX) and the secondDRX-related second information (the UE specific eDRX value) in therequest message (the ATTACH REQUEST or TAU REQUEST message) and transmitthe request message to the MME. In this case, the first DRX-relatedsecond information may include the first DRX cycle information preferredby the UE, and the second DRX-related second information may include thesecond DRX cycle information preferred by the UE. The cycle informationpreferred by the UE may mean cycle information determined to be appliedby the UE.

In addition, at step S660, the UE may receive a response message (e.g.,the ATTACH ACCEPT or TAU ACCEPT message) corresponding to the requestmessage from the MME.

At step S670, the UE that receives the response message may determinewhether the response message includes the second DRX-related thirdinformation (the allowed eDRX parameter). The second DRX-related thirdinformation (the allowed eDRX parameter) may include informationindicating whether the MME supports the second DRX (eDRX), or the secondDRX cycle information (the eDRX cycle information) having to be appliedby the UE.

If the response message includes the second DRX-related thirdinformation, the UE may perform an RRC connection release process atstep S675.

At step S680, the UE that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, at step S685, the UE may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, at step S690, the UE may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

Meanwhile, if the eNB does not broadcast the second DRX-related firstinformation and the paging-related second parameter (nB′) at step S630,or if the MME does not transmit the second DRX-related third information(the allowed eDRX parameter) at step S670, the UE may perform only thefirst DRX (typical DRX) process at step S695.

FIG. 7 is a diagram illustrating an eNB operation according to the firstmethod of the first embodiment of the present invention.

Referring to FIG. 7, at step S710, the eNB may determine whether the eNBsupports the second DRX (eDRX).

At step S720, the eNB may broadcast system information. If the eNBsupports the second DRX, the eNB may broadcast, to the UE, the systeminformation including the second DRX-related first information and thepaging-related second parameter (nB′) as well as the first DRX-relatedfirst information and the paging-related first parameter which are thefirst DRX configuration information.

If the eNB does not support the second DRX, the eNB may broadcast thesystem information including only the first DRX configurationinformation at step S730. If the eNB does not support the second DRX,the eNB may operate according to the first DRX as described withreference to FIG. 4, and a detailed description will be omitted.

If the eNB supports the second DRX, the eNB may receive paging forspecific UE from the MME at step S740.

At step S750, the eNB that receives the paging may determine whether thepaging information includes the second DRX-related third information.

If the paging information includes the second DRX-related thirdinformation, the eNB may determine at step S760 the first DRX cycle (T)by selecting a smaller value between the first DRX-related firstinformation (the default DRX) and the first DRX-related secondinformation (the UE specific DRX value). In addition, the eNB mayselect, as the second DRX cycle, the second DRX cycle informationindicated by the second DRX-related third information included in thepaging information.

Alternatively, the eNB may determine the second DRX (eDRX) cycle (T′) byselecting a smaller value (or larger value) between the secondDRX-related first information and the second DRX-related thirdinformation received from the MME.

If the paging information does not include the second DRX-related thirdinformation, the eNB may determine at step S770 the first DRX cycle (T)by selecting a smaller value between the first DRX-related firstinformation (the default DRX) and the first DRX-related secondinformation (the UE specific DRX value).

Thereafter, at step S780, the eNB may transmit the paging by calculatingthe PHF, PF, and PO based on at least one of the second DRX cycle (T′)and the first DRX cycle (T). That is, if the second DRX-related thirdinformation is not included in the paging information received from theMME, the eNB may transmit the paging by using only the first DRX cycle.Also, if the second DRX-related third information is included in thepaging information received from the MME, the eNB may transmit thepaging based on the second DRX cycle (T′) and the first DRX cycle (T).Specifically, when the second DRX cycle arrives, the eNB may repeatedlytransmit the paging in a specific period (PTW) according to the firstDRX cycle. At this time, even when the second DRX cycle arrives, thestarting point of the first DRX cycle may be changed depending on theUE.

FIG. 8 is a diagram illustrating an MME operation according to the firstmethod of the first embodiment of the present invention.

Referring to FIG. 8, the MME may receive a request message from the UE.At step S810, the MME may determine whether the request message (theATTACH REQUEST or TAU REQUEST message) including the second DRX-relatedsecond information (the UE specific eDRX) is received from the UE.

If the request message including the second DRX-related secondinformation is received, the MME may determine at step S820 whether theMME can support the second DRX (eDRX).

If the MME supports the second DRX, the MME may transmit a responsemessage at step S830. At this time, the MME may include the secondDRX-related third information (the allowed eDRX parameter) in theresponse message (the ATTACH ACCEPT or TAU ACCEPT message) and transmitit to the UE. In this case, the second DRX-related third information maybe identical with the second DRX-related second information or includethe second DRX cycle information determined by the MME.

Thereafter, at step S840, the paging for the UE may be triggered.

When the paging is triggered, the MME may further provide the secondDRX-related third information together with the paging to the eNB atstep S850. That is, the MME may transmit the paging including the secondDRX-related third information to the eNB.

If the second DRX-related second information is not received from theUE, or if the MME does not support the second DRX (eDRX), the MME mayperform an operation according to the first DRX at step S860. That is,the MME may transmit the response message to the UE and transmit thepaging message including the first DRX-related second information to theeNB.

Second Method

The second method is characterized in that the eNB broadcasts the secondDRX (eDRX) configuration information (or the second DRX parameter) onlywhen all the eNBs and MMEs forming one TA support eDRX.

The eNB may broadcast the second DRX (eDRX) parameter as the systeminformation when all the MMEs connected thereto support the second DRX(eDRX). Therefore, contrary to the first method, the MME does not needto notify the UE whether the second DRX (eDRX) is supported, using aresponse message (the ATTACH ACCEPT or TAU ACCEPT message).

FIG. 9 is a diagram illustrating a process of determining a second DRXcycle by UE according to a second method of the first embodiment of thepresent invention.

Referring to FIG. 9, the eNB 903 may broadcast the system information atstep S910. If all the eNBs forming the TA and related MMEs support thesecond DRX (eDRX), the eNB 903 may broadcast the second DRX-relatedfirst information.

Therefore, the UE 901 may receive the system information from the eNB atstep S920. For example, the UE may receive SIB2 and SIBx. In this case,the SIB2 may include the first DRX-related first information (thetypical default DRX value), and the SIBx may include the secondDRX-related first information.

The second DRX-related first information may include information (anindicator) indicating whether the second DRX is supported, or a defaulteDRX value. The second DRX-related first information may be included ina typical SIB or a newly defined SIB. For example, the secondDRX-related first information may be included in SIB 1.

In addition, at step S930, the UE may provide the second DRX-relatedsecond information to the MME. Specifically, if the eNB is broadcastingthe second DRX-related first information, and if the UE decides that itis necessary to apply the second DRX (eDRX), the UE may provide thesecond DRX-related second information (a desired UE specific DRX value)to the MME 905. At this time, the second DRX-related second informationmay include the second DRX cycle information desired by the UE.

The UE may transmit a request message to the MME at step S940. Using therequest message (e.g., the ATTACH REQUEST or TAU REQUEST message), theUE may transmit the first DRX-related second information (the UEspecific DRX value) and the second DRX-related second information (theUE specific eDRX value).

As described above, the first DRX-related second information may includecycle information desired by the UE for the first DRX, and the secondDRX-related second information may include cycle information desired bythe UE for the second DRX.

In addition, at step S950, the UE may determine the DRX period.

The UE may determine the first DRX cycle (T) by selecting a smallervalue between the first DRX-related first information (the default DRXvalue) and the first DRX-related second information (the UE specificDRX). Also, the UE may select, as the second DRX cycle, the secondDRX-related second information transmitted to the MME. Alternatively,the UE may determine the second DRX (eDRX) cycle (T′) by selecting asmaller or larger value between the second DRX-related first informationand the second DRX-related second information (the UE specific eDRX).

If the second DRX-related first information is not broadcasted from theeNB, the UE may determine only the first DRX cycle (T) by using asmaller value between the first DRX-related first information (thetypical default DRX value) and the first DRX-related second information(the UE specific DRX).

Meanwhile, the MME that receives the request message may transmit pagingto the eNB at step S960. At this time, together with the paging for theUE, the MME may transmit the first DRX-related second information (theUE specific DRX) and the second DRX-related second information (the UEspecific eDRX value) to the eNB.

However, if the eNB does not broadcast the second DRX-related firstinformation, only the first DRX-related second information may beincluded in the paging.

Therefore, the eNB may determine the DRX cycle at step S970. The eNB maydetermine the DRX cycle (T) by selecting a smaller value between thefirst DRX-related first information (the default DRX value) and thefirst DRX-related second information (the UE specific DRX).

In addition, the eNB may determine, as the second DRX, the secondDRX-related second information received from the MME. Alternatively, theeNB may determine the second DRX (eDRX) cycle (T′) by selecting asmaller or larger value between the second DRX-related first informationand the second DRX-related second information (the UE specific eDRX).However, if the eNB does not broadcast the second DRX-related firstinformation, the process of determining the second DRX cycle may beomitted.

Accordingly, using the determined second DRX cycle and the first DRXcycle, the UE may perform the DRX operation.

Meanwhile, the UE may move and, after performing cell reselection, campon a new serving cell. The UE may acquire system information broadcastedby the serving cell, for example, the first DRX-related firstinformation (the default DRX cycle) and the paging-related firstparameter (the nB value) from the SIB 2, and the second DRX-relatedfirst information and the paging-related second parameter (the nB′value) from the SIB x. At this time, if the following two conditions aresatisfied, the UE determines to apply the second DRX (eDRX).

(1) The second DRX-related second information (the UE eDRX) istransmitted to the MME in the current TA.

(2) The second DRX-related first information (or the second DRX (eDRX)parameter) is included in the system information of the current servingcell.

On the other hand, if either of the following conditions is satisfied,the UE does not apply the second DRX (eDRX).

(1) The second DRX-related second information (the UE eDRX) is nottransmitted to the MME in the current TA.

(2) Although the second DRX-related second information is transmitted tothe MME in the current TA, the second DRX-related first information (orthe second DRX (eDRX) parameter) is not included in the systeminformation of the current serving cell.

If the UE determines to apply the second DRX (eDRX), the UE may select,as the second DRX cycle, the second DRX-related second informationtransmitted to the MME. Alternatively, the UE may determine the secondDRX cycle (T′) by selecting a smaller or larger value between the secondDRX-related first information and the second DRX-related secondinformation (Min (or Max) [default eDRX, UE eDRX]).

In addition, the UE may determine the first DRX cycle (T) by selecting asmaller value between the first DRX-related first information and thefirst DRX-related second information (Min [default DRX, UE DRX]).Therefore, the UE may determine the PHF by using the second DRX cycle(T′) and determine the PF by using the first DRX cycle (T). As describedabove, the UE does not perform the paging monitoring in the HF which isnot the PHF, and may perform the paging monitoring in the PF of the HFwhich is the PHF.

On the other hand, if the UE determines to apply the first DRX (not toapply the second DRX), the UE may determine the first DRX cycle (T) byselecting a smaller value between the first DRX-related firstinformation and the first DRX-related second information (Min [defaultDRX, UE DRX]). At this time, the second DRX cycle (T′) may be regardedas 1 (that is, all the HFs are regarded as the PHF), or thepaging-related second parameter (nB′) may be set as the second DRX cycle(T′) (likewise, all the HFs may be regarded as the PHF). Therefore, theUE may perform the paging monitoring in the PF of all the HFs.

Thereafter, the MME may receive incoming data from the S-GW. If thecurrent TA of target UE to which the incoming data is to be transmittedis TA x, and if all serving cells of the TA x support the second DRX(eDRX), the MME may generate a paging message including the firstDRX-related second information (the UE DRX cycle) and the secondDRX-related second information (the UE specific eDRX cycle) and transmitthe generated paging message to the eNB.

If the serving cells of the TA x do not support the second DRX (eDRX),or if the second DRX-related second information (the UE specific eDRXvalue) is not received from the UE, the MME may generate a pagingmessage including the first DRX-related second information (the UE DRXcycle) and transmit it to the eNB.

FIG. 10 is a diagram illustrating a UE operation according to the secondmethod of the first embodiment of the present invention.

Referring to FIG. 10, at step S1010, the UE may be powered on, or thetracking area (TA) may be changed.

At step S1020, the UE may acquire system information from the eNB.

At step S1030, the UE that acquires the system information may identifywhether the system information includes the second DRX configurationinformation. That is, the UE may determine whether the systeminformation includes the second DRX-related first information and thepaging-related second parameter (the nB′ value).

If the system information includes the second DRX-related firstinformation and the paging-related second parameter (the nB′ value), theUE may perform an RRC connection establishment process at step S1040.

After the RRC connection is completed, the UE may transmit a requestmessage to the MME at step S1050. If the UE prefers to apply the secondDRX (eDRX) or if the UE supports the second DRX, the UE may include thefirst DRX-related second information (the UE specific DRX) and thesecond DRX-related second information (the UE specific eDRX value) inthe request message (the ATTACH REQUEST or TAU REQUEST message) andtransmit the request message to the MME. As described above, the firstDRX-related second information may include the first DRX cycleinformation preferred by the UE, and the second DRX-related secondinformation may include the second DRX cycle information preferred bythe UE. The cycle information preferred by the UE may mean cycleinformation determined to be applied by the UE.

In addition, at step S1060, the UE may receive a response message (e.g.,the ATTACH ACCEPT or TAU ACCEPT message) corresponding to the requestmessage from the MME.

At step S1070, the UE that receives the response message may perform anRRC connection release process.

At step S1075, the UE that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, at step S1080, the UE may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, at step S1085, the UE may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

Meanwhile, if the eNB does not broadcast the second DRX-related firstinformation and the paging-related second parameter (nB′) at step S1030,the UE may perform only the first DRX (typical DRX) process at stepS1090.

FIG. 11 is a diagram illustrating an eNB operation according to thesecond method of the first embodiment of the present invention.

Referring to FIG. 11, at step S1110, the eNB may determine whether allthe eNBs and MMEs forming its own TA support the second DRX (eDRX).

At step S1120, the eNB may broadcast system information. If all the eNBsand MMEs support the second DRX, the eNB may broadcast, to the UE, thesystem information including the second DRX-related first informationand the paging-related second parameter (nB′) as well as the firstDRX-related first information and the paging-related first parameterwhich are the first DRX (typical DRX) configuration information.

If all the eNBs and MMEs do not support the second DRX, the eNB maybroadcast the system information including only the first DRX (typicalDRX) configuration information at step S1130. If the eNB does notsupport the second DRX, the eNB may operate according to the first DRXas described with reference to FIG. 4, and a detailed description willbe omitted.

If all the eNBs and MMEs support the second DRX, the eNB may receivepaging for the UE from the MME at step S1140.

At step S1150, the eNB that receives the paging may determine whetherthe paging information includes the second DRX-related secondinformation (the UE specific eDRX value).

If the paging information includes the second DRX-related secondinformation, the eNB may determine at step S1160 the first DRX cycle (T)by selecting a smaller value between the first DRX-related firstinformation (the default DRX) and the first DRX-related secondinformation (the UE specific DRX value). In addition, the eNB mayselect, as the second DRX cycle, the second DRX-related secondinformation included in the paging information.

Alternatively, the eNB may determine the second DRX (eDRX) cycle (T′) byselecting a smaller value (or larger value) between the secondDRX-related first information and the second DRX-related secondinformation (the UE specific eDRX value).

If the paging information does not include the second DRX-related secondinformation, the eNB may determine at step S1170 the first DRX cycle (T)by selecting a smaller value between the first DRX-related firstinformation (the default DRX) and the first DRX-related secondinformation (the UE specific DRX value).

Thereafter, at step S1180, the eNB may transmit the paging bycalculating the PHF, PF, and PO based on at least one of the second DRXcycle information (T′) and the first DRX cycle information (T). That is,if the second DRX-related second information is not included in thepaging information received from the MME, the eNB may transmit thepaging by using only the first DRX cycle information. Also, if thesecond DRX-related second information is included in the paginginformation received from the MME, the eNB may transmit the paging basedon the second DRX cycle information (T′) and the first DRX cycleinformation (T).

Specifically, when the second DRX cycle arrives, the eNB may repeatedlytransmit the paging in a specific period (PTW) according to the firstDRX cycle. At this time, even when the second DRX cycle arrives, thestarting point of the first DRX cycle may be changed depending on theUE.

FIG. 12 is a diagram illustrating an MME operation according to thesecond method of the second embodiment of the present invention.

Referring to FIG. 12, the MME may receive a request message from the UE.At step S1210, the MME may determine whether the request message (theATTACH REQUEST or TAU REQUEST message) including the second DRX-relatedsecond information (the UE specific eDRX) is received from the UE.

If the request message including the second DRX-related secondinformation is received, the paging for the UE may be triggered at stepS1220.

When the paging is triggered, the MME may further provide the secondDRX-related second information (the UE specific eDRX value) togetherwith the paging to the eNB at step S1230. That is, the MME may transmitthe paging including the second DRX-related second information to theeNB.

If the second DRX-related second information (the UE specific eDRXvalue) is not received from the UE, or if the MME does not support thesecond DRX (eDRX), the MME may perform an operation according to thefirst DRX at step S1240. That is, the MME may transmit the responsemessage to the UE and transmit the paging message including the firstDRX-related second information to the eNB.

FIG. 13 illustrates a configuration of UE according to the presentinvention.

Referring to FIG. 13, the UE may include a radio frequency (RF)processor 1310, a baseband processor 1320, a storage 1330, and acontroller 1340.

The RF processor 1310 may perform a function, such as band conversionand amplification of a signal, for transmitting and receiving the signalthrough a wireless channel. That is, the RF processor 1310 mayup-convert a baseband signal provided from the baseband processor 1320into an RF band signal to transmit the RF band signal through anantenna, and also down-convert an RF band signal received through theantenna into a baseband signal. For example, the RF processor 1310 mayinclude a transmitter filter, a receiver filter, an amplifier, a mixer,an oscillator, a digital to analog converter (DAC), an analog to digitalconverter (ADC), and the like. Although FIG. 13 shows only one antenna,the UE may have a plurality of antennas. In addition, the RF processor1310 may include a plurality of RF chains. Further, the RF processor1310 may perform beamforming. For the beamforming, the RF processor 810may adjust the phase and size of signals transmitted and receivedthrough a plurality of antennas or antenna elements.

The baseband processor 1320 may perform a conversion function between abaseband signal and a bit stream in accordance with a physical layerstandard of the system. For example, in data transmission, the basebandprocessor 1320 may create complex symbols by encoding and modulatingtransmission bit streams. Also, in data reception, the basebandprocessor 1320 may restore reception bit streams by demodulating anddecoding a baseband signal provided from the RF processor 1310. In caseof complying with orthogonal frequency division multiplexing (OFDM)scheme, in data transmission, the baseband processor 1320 may generatecomplex symbols by encoding and modulating transmission bit streams, mapthe complex symbols to subcarriers, and construct OFDM symbols throughan inverse fast Fourier transform (IFFT) operation and a cyclic prefix(CP) insertion. In addition, in data reception, the baseband processor1320 may divide a baseband signal provided from the RF processor 1310into OFDM symbol units, restore signals mapped to subcarriers through afast Fourier transform (FFT) operation, and restore reception bitstreams through demodulation and decoding.

The baseband processor 1320 and the RF processor 1310 may transmit andreceive a signal as described above. Accordingly, the baseband processor1320 and the RF processor 1310 may be referred to as a transmittingunit, a receiving unit, a transceiver, or a communication unit. Inaddition, at least one of the baseband processor 820 and the RFprocessor 1310 may include a plurality of communication modules tosupport a plurality of different wireless access technologies. Also, atleast one of the baseband processor 1320 and the RF processor 1310 mayinclude different communication modules for processing signals ofdifferent frequency bands. For example, the different wireless accesstechnologies may include a wireless LAN (e.g., IEEE 802.11), a cellularnetwork (e.g., LTE), and the like. In addition, the different frequencybands may include a super high frequency (SHF) band (e.g., 2.5 GHz, 5GHz), and a millimeter wave (e.g., 60 GHz) band.

The storage 1330 may store a basic program for the operation of the UE,an application program, and data such as setting information. Inparticular, the storage 1330 may store information associated with asecond access node that performs wireless communication by using asecond wireless access technology. Also, the storage 1330 may providethe stored data in response to a request of the controller 1340.

The controller 1340 may control overall operations of the UE. Forexample, the controller 1340 may transmit and receive a signal throughthe baseband processor 1320 and the RF processor 1310. Also, thecontroller 1340 writes and read data to and from the storage 1340. Forthis, the controller 1340 may include at least one processor. Forexample, the controller 1340 may include a communication processor (CP)for perform the control for communication and an application processor(AP) for controlling an upper layer such as an application program.According to an embodiment of the present invention, the controller 1340may control the UE to perform the above-described operations andprocedures of the UE.

Specifically, the controller 1340 may acquire system information fromthe eNB. Also, the controller 1340 may identify whether the second DRXconfiguration information is included in the system information. Thatis, the controller 1340 may determine whether the second DRX-relatedfirst information and the paging-related second parameter (the nB′value) are included in the system information.

Also, the controller 1340 may perform an RRC connection establishmentprocess. In addition, the controller 1340 may transmit a requestmessage. The request message may include, for example, an attach requestmessage or a TAU request message. The controller 1340 may include thefirst DRX-related second information and the second DRX-related secondinformation in the request message to be transmitted to the MME.

In addition, the controller 1340 may receive a response message (e.g.,an ATTACH ACCEPT or TAU ACCEPT message) corresponding to the requestmessage.

The controller 1340 may determine whether the second DRX-related thirdinformation (the allowed eDRX parameter) is included in the responsemessage. The second DRX-related third information (the allowed eDRXparameter) may include information indicating whether the MME supportsthe second DRX (eDRX), or the second DRX cycle information (the eDRXcycle information) having to be applied by the UE. However, according tothe second method for broadcasting the second DRX configurationinformation at the eNB only when all the eNBs and MMEs forming one TAsupport the second DRX, the controller 1340 may omit a process ofdetermining whether the second DRX-related third information isincluded.

The controller 1340 may perform an RRC connection release process. Thecontroller 1340 that releases the RRC connection may operate by applyingthe second DRX (eDRX).

Specifically, using the above-described method, the controller 1340 mayderive the second DRX cycle (T′) and the first DRX cycle (T) and thendetermine the PHF and the PF. This step may be performed previouslybefore the RRC connection release.

In addition, the controller 1340 may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

On the other hand, if the eNB does not broadcast the second DRX-relatedfirst information and the paging-related second parameter (nB′), or ifthe MME does not transmit the second DRX-related third information (theallowed eDRX parameter, the controller may perform only the first DRX(typical DRX) process.

FIG. 14A illustrates a block configuration of eNB according to thepresent invention.

As shown in FIG. 14A, the eNB may include an RF processor 1410, abaseband processor 1420, a backhaul communication unit 1430, a storage1440, and a controller 1450.

The RF processor 1410 may perform a function, such as band conversionand amplification of a signal, for transmitting and receiving the signalthrough a wireless channel. That is, the RF processor 1410 mayup-convert a baseband signal provided from the baseband processor 1420into an RF band signal to transmit the RF band signal through anantenna, and also down-convert an RF band signal received through theantenna into a baseband signal. For example, the RF processor 1410 mayinclude a transmitter filter, a receiver filter, an amplifier, a mixer,an oscillator, a DAC, an ADC, and the like. Although FIG. 9 shows onlyone antenna, the first access node may have a plurality of antennas. Inaddition, the RF processor 1410 may include a plurality of RF chains.Further, the RF processor 1410 may perform beamforming. For thebeamforming, the RF processor 1410 may adjust the phase and size ofsignals transmitted and received through a plurality of antennas orantenna elements.

The baseband processor 1420 may perform a conversion function between abaseband signal and a bit stream in accordance with a physical layerstandard of the first wireless access technology. For example, in datatransmission, the baseband processor 1420 may create complex symbols byencoding and modulating transmission bit streams. Also, in datareception, the baseband processor 1420 may restore reception bit streamsby demodulating and decoding a baseband signal provided from the RFprocessor 1410. In case of complying with OFDM scheme, in datatransmission, the baseband processor 1420 may generate complex symbolsby encoding and modulating transmission bit streams, map the complexsymbols to subcarriers, and construct OFDM symbols through an IFFToperation and a CP insertion. In addition, in data reception, thebaseband processor 1420 may divide a baseband signal provided from theRF processor 1410 into OFDM symbol units, restore signals mapped tosubcarriers through an FFT operation, and restore reception bit streamsthrough demodulation and decoding. The baseband processor 1420 and theRF processor 1410 may transmit and receive a signal as described above.Thus, the baseband processor 1420 and the RF processor 1410 may bereferred to as a transmitting unit, a receiving unit, a transceiver, acommunication unit, or a wireless communication unit.

The backhaul communication unit 1430 may provide an interface forperforming communication with other node in the network. That is, thebackhaul communication unit 1430 may convert a bit stream transmittedfrom the main eNB to another node, e.g., a sub-eNB, a core network,etc., into a physical signal, and may also convert a physical signalreceived from such other node into a bit stream.

The storage 1440 may store a basic program for the operation of the maineNB, an application program, and data such as setting information. Inparticular, the storage 1440 may store information on a bearer allocatedto connected UE, a measurement result reported from the connected UE,and the like. In addition, the storage 940 may store information fordetermining whether to provide or suspend multiple connections to orfrom the UE. Also, the storage 1440 may provide the stored data inresponse to a request of the controller 1450.

The controller 1450 may control overall operations of the main eNB. Forexample, the controller 1450 may transmit and receive a signal throughthe baseband processor 1420 and the RF processor 1410 or through thebackhaul communication unit 1430. Also, the controller 1450 writes andread data to and from the storage 1440. For this, the controller 1450may include at least one processor. According to an embodiment of thepresent invention, the controller 1450 may include a multi-connectioncontroller 1452 for performing control for providing multipleconnections to the UE. For example, the controller 1450 may control theeNB to perform the above-described operations and procedures.

Specifically, the controller 1450 may determine whether the eNB supportsthe second DRX.

The controller 1450 may broadcast system information. If the eNBsupports the second DRX, the controller 1450 may broadcast, to the UE,the system information including the second DRX-related firstinformation and the paging-related second parameter (nB′) as well as thefirst DRX-related first information and the paging-related firstparameter which are the first DRX configuration information.

On the other hand, according to the second method, in case where all theeNBs and MMEs forming the TA to which the eNB belongs support the secondDRX (eDRX), the controller 1450 may broadcast the system informationincluding the second DRX configuration information.

If the eNB does not support the second DRX, the controller 1450 maybroadcast the system information including only the first DRXconfiguration information. If the eNB does not support the second DRX,the controller 1450 may operate according to the first DRX.

If the eNB supports the second DRX, the controller 1450 may receivepaging for specific UE from the MME.

In addition, the controller 1450 may determine whether the paginginformation includes the second DRX-related third information (theallowed eDRX parameter).

If the paging information includes the second DRX-related thirdinformation, the controller 1450 may determine the first DRX cycle (T)by selecting a smaller value between the first DRX-related firstinformation (the default DRX) and the first DRX-related secondinformation (the UE specific DRX value). In addition, the controller1450 may select, as the second DRX cycle, the second DRX cycleinformation indicated by the second DRX-related third informationincluded in the paging information.

Alternatively, the controller 1450 may determine the second DRX (eDRX)cycle (T′) by selecting a smaller value (or larger value) between thesecond DRX-related first information and the second DRX-related thirdinformation (the allowed eDRX parameter) received from the MME.

If the paging information does not include the second DRX-related thirdinformation, the controller 1450 may determine the first DRX cycle (T)by selecting a smaller value between the first DRX-related firstinformation (the default DRX) and the first DRX-related secondinformation (the UE specific DRX value).

On the other hand, according to the second method, the controller 1450may determine whether the second DRX-related second information isincluded in a paging message. Therefore, if the second DRX-relatedsecond information is included in the paging message, the controller1450 may select, as the second DRX cycle, the second DRX-related secondinformation. Alternatively, the controller 1450 may determine the secondDRX (eDRX) cycle (T′) by selecting a smaller value (or larger value)between the second DRX-related first information and the secondDRX-related second information (the UE specific eDRX value). Also, thecontroller 1450 may determine the first DRX cycle (T) by selecting asmaller value between the first DRX-related first information (thedefault DRX) and the first DRX-related second information (the UEspecific DRX value).

Thereafter, the controller 1450 may transmit the paging by calculatingthe PHF, PF, and PO based on at least one of the second DRX cycle (T′)and the first DRX cycle (T). That is, if the second DRX-related thirdinformation (in case of the first method) or the second DRX-relatedsecond information (in case of the second method) is not included in thepaging information received from the MME, the controller 1450 maytransmit the paging by using only the first DRX cycle. Also, if thesecond DRX-related third information (in case of the first method) orthe second DRX-related second information (in case of the second method)is included in the paging information received from the MME, thecontroller 1450 may transmit the paging based on the second DRX cycle(T′) and the first DRX cycle (T). Specifically, when the second DRXcycle arrives, the controller 1450 may repeatedly transmit the paging ina specific period (PTW) according to the first DRX cycle. At this time,even when the second DRX cycle arrives, the starting point of the firstDRX cycle may be changed depending on the UE.

FIG. 14B is a diagram illustrating a configuration of an MME accordingto an embodiment of the present invention.

Referring to FIG. 14B, the MME may include a transceiver 1470, acontroller 1471, and a storage 1472.

The transceiver 1470 may transmit and receive a signal to and from othernetwork entity. The transceiver 1470 may receive a request message fromthe UE, transmit a response message to the UE, and transmit a pagingmessage to the eNB.

The controller 1471 may receive a request message from the UE. Thecontroller 1471 may determine whether the request message (the ATTACHREQUEST or TAU REQUEST message) including the second DRX-related secondinformation (the UE specific eDRX) is received from the UE.

If the request message including the second DRX-related secondinformation is received, the controller 1471 may determine whether theMME can support the second DRX (eDRX).

However, in case of the second method, the controller 1471 may omit theabove step.

The controller 1471 may transmit a response message to the UE. At thistime, the controller 1471 may include the second DRX-related thirdinformation (the allowed eDRX parameter) in the response message andtransmit it to the UE. Alternatively, in case of the second method, thecontroller 1471 may include the second DRX-related second information inthe response message and transmit it to the UE.

In addition, when the paging is triggered, the controller 1471 mayfurther provide the second DRX-related third information (the allowedeDRX parameter) together with the paging to the eNB. That is, thecontroller 1471 may transmit the paging including the second DRX-relatedthird information to the eNB. Alternatively, in the second method, thecontroller 1471 may further provide the second DRX-related secondinformation (the UE specific eDRX value) together with the paging to theeNB. That is, the controller 1471 may transmit the paging including thesecond DRX-related second information to the eNB.

If the second DRX-related third information (in case of the firstmethod) or the second DRX-related second information (in case of thesecond method) is not received from the UE, or if the MME does notsupport the second DRX (eDRX), the controller 1471 may perform anoperation according to the first DRX. That is, the controller 1471 maytransmit the response message to the UE and transmit the paging messageincluding the first DRX-related second information to the eNB.

Meanwhile, in case where the UE operates according to the second DRXhaving the second DRX cycle, a problem may occur when the systeminformation is changed. Specifically, a modification period (MP) may beset in the UE that operates in the DRX mode. If the system informationis updated in the (m+1)-th MP, the eNB may notify a change of the systeminformation to the UE in the preceding MP through a paging message.However, in case of the second DRX, the cycle of DRX may be extended andthus be longer than the maximum value of the MP, and the UE may notreceive the paging in the preceding MP. Therefore, a method fornotifying whether the system information is changed is needed.

Second Embodiment

FIG. 15 is a diagram illustrating a process of changing systeminformation.

The system information broadcasted by the eNB may be changed, based on amodification period (MP). Excepting some system information, the eNB maybroadcast newly changed system information from a start point of eachMP. Also, in the MP before the newly changed system information isbroadcasted, the eNB may notify the UEs that the changed systeminformation will be broadcasted from the next MP. For example, if thechanged system information is broadcasted from the (n+1)-th MP 1520, theeNB may notify, in the preceding n-th MP, the UEs that the systeminformation will be changed from the next MP.

Using the paging message, the eNB may notify whether the systeminformation is changed. In order to check whether the system informationis changed, the UE should receive the paging at least once within theMP. If a system information change indicator (systemInfoModification IE)is included in the paging message, it means that newly updated systeminformation will be transmitted from the next period of the MP in whichthe paging is transmitted. For example, the system information changeindicator may be formed of one bit.

Excepting some system information, when the system information ischanged, the eNB may increase, by one, system information change relatedinformation (hereinafter, systemInfoValueTag, valuetag, etc., may beused alternatively) included in the SIB1. The system information changerelated information (systemInfoValueTag) may be used for the UE, whichcamps on again from the out-of-coverage state, to determine whether thesystem information stored therein is identical with the systeminformation currently being broadcasted. Using the paging message or thesystemInfoValueTag of the SIB1, the UE may determine whether the systeminformation is changed.

However, if the DRX cycle is extended longer than the maximum value ofthe MP so as to reduce power consumption, the UE may not receive thepaging within the MP. In this case, the UE cannot check whether thesystem information is newly updated. In addition, when the systeminformation is changed, the UE may not receive the paging messagebecause the configuration information for the paging message is changed.Therefore, a method for solving this problem is needed.

This embodiment is characterized in that, for the second DRX (eDRX) UE,depending on the type of the system information, a method for includingthe system information change indicator in the paging and notifying itto the UE is applied in case of the update of the specific systeminformation, and a method for checking (on-demand SIB1 checking) theupdate of the other system information by using the system informationchange related information is applied.

In the present invention, the UE that operates in the first DRX mode maybe notified of the change of the system information through a firstsystem information change indicator (systemInfoModification-DRX), andthe UE that operates in the second DRX mode may be notified of thechange of the system information through a second system informationchange indicator (systemInfoModification-eDRX).

Specifically, if the first system information is updated in the (m+1)-thMP, the paging message may be transmitted through all available PFs andPOs of all available PHFs after the (m+1)-th MP. If the second systeminformation is updated in the (m+1)-th MP, the eNB does not transmit aseparate paging message for the second DRX (eDRX) UE. In this case, whenthe UE triggers the RRC connection, the UE may check the systeminformation change related information (ValueTag information) containedin the SIB1 and thereby determine whether the system information isupdated. As described above, the PO refers to a subframe fortransmitting the paging message in the PF. The eNB may transmit thepaging message in the PO of the corresponding PF. In the presentinvention, it may be represented that the paging message is transmittedin the PF and PO, in the PF/PO, in the PF, or in the PO.

In the present invention, the system information (SI) necessary forreceiving the paging message at the UE may be defined as first systeminformation. When the paging message is used to indicate whether the SIis updated, a messaging message should be transmitted for a long time.Therefore, in order to reduce the signaling overhead caused by this,most update of the SI complies with a method for using the systeminformation change related information when the RRC connection of the UEis triggered.

However, in order to determine whether an RRC connection establishmentis performed, the UE should be able to receive the paging message at aminimum. Therefore, only when the system information necessary forreceiving the paging message is updated, this update may be notified tothe UE through the paging message. In the present invention, systeminformation other than the first system information may be defined asthe second system information.

The first system information may include system information related toreception of the paging message and to mobility. For example, the firstsystem information may include cell access related information(CellAccessRelatedInfo), paging control channel configurationinformation (PCCH-config), cell list information(intraFreqNeighCellList), and the like. The second system informationmay include system information related to the RRC connectionconfiguration, for example, access barring configuration information(AC-BarringConfig), random access control channel configurationinformation (RACH-config), and the like.

Details of the first system information and the second systeminformation will be described later.

When the first system information is updated in the (m+1)-th MP, the eNBmay transmit the paging message through all available Pos of allavailable PFs in the m-th MP for the first DRX (typical DRX) UE. Inaddition, for the second DRX (eDRX) UE, the eNB may transmit the pagingmessage through all available POs of all available PFs in all availablePHFs after the MP [m+1].

In this case, DRX parameters (configurable parameter) may be introducedto control the number of available PHFs, available PFs, and availablePOs. In the DRX parameters, the parameter for the first DRX (typicalDRX) and the parameter for the second DRX (eDRX) may be configuredindependently. Therefore, the PF and PO for the first DRX (typical DRX)and the PF and PO for the second DRX (eDRX) may be configured indifferent radio frames or subframes.

The DRX parameters (configurable parameter) may include thepaging-related first parameter (nB). In the present invention, thepaging-related first parameter (nB) for typical PF and PO, thepaging-related second parameter (nB′) for the PF and PO applied to thesecond DRX (eDRX), and the paging-related third parameter (nB″) for thePHF may be defined individually. In the present invention, one of thefollowing signaling options may be used.

Case 1: The eNB may transmit the paging-related first parameter (nB) andthe first DRX-related first information (default DRX cycle) through theSIB2 and also transmit the second DRX-related first information throughthe SIBx.

Therefore, the UE may derive the PHF by using the paging-related firstparameter (nB) and the first DRX-related first information (default DRXcycle) and also derive the PF and PO by using the paging-related firstparameter (nB) and the first DRX-related first information (default DRXcycle).

The case 1 is characterized by applying the same paging-related firstparameter (nB) to the first DRX (typical DRX) and the second DRX (eDRX),and has a disadvantage of being incapable of optimizing the number ofPHFs.

Case 2-1: The eNB may transmit the paging-related first parameter (nB)and the first DRX-related first information (default DRX cycle) throughthe SIB2, and also transmit the paging-related second parameter (nB′)and the second DRX-related first information through the SIBx.

Therefore, the UE may derive the PHF by using the paging-related secondparameter (nB′) and the second DRX-related first information. Also, theUE may derive the PF and PO by using the paging-related first parameter(nB) and the first DRX-related first information (default DRX cycle).

Accordingly, in the case 2-1, it is possible to optimize the number ofPHFs by appropriately adjusting the paging-related second parameter (nB′value). However, it is impossible to optimize the number of PFs.

Case 2-2: The eNB may transmit the paging-related first parameter (nB)and the first DRX-related first information (default DRX cycle) throughthe SIB2, and also transmit the paging-related second parameter (nB′)and the second DRX-related first information through the SIBx.

Therefore, the UE may derive the PHF by using the paging-related secondparameter (nB′) and the second DRX-related first information. Also, theUE may derive the PF and PO by using the paging-related second parameter(nB′) and the first DRX-related first information (default DRX cycle foreDRX UE).

Accordingly, in the case 2-2, it is possible to optimize the number ofPHFs and the number of PFs by appropriately adjusting the paging-relatedsecond parameter (nB′ value). However, individual optimization is notpossible.

Case 3: The eNB may transmit the paging-related first parameter (nB) andthe first DRX-related first information (default DRX cycle) through theSIB2, and also transmit the paging-related second parameter (nB′), thepaging-related third parameter (nB″), and the second DRX-related firstinformation through the SIBx.

Therefore, the UE may derive the PHF by using the paging-related secondparameter (nB′) and the second DRX-related first information. Also, theUE may derive the PF and PO by using the paging-related third parameter(nB″) and the first DRX-related first information (default DRX cycle foreDRX UE).

Accordingly, in the case 3, it is possible to optimize the number ofPHFs by appropriately adjusting the paging-related second parameter (nB′value). Also, it is possible to optimize the number of PFs byappropriately adjusting the paging-related third parameter (nB″ value).

When the second system information is updated in the (m+1)-th MP, theeNB may transmit the paging message through all available POs of allavailable PFs in the m-th MP for the first DRX (typical DRX) UE.However, the eNB may not transmit a separate paging message for thesecond DRX (eDRX) UE. Instead, when an actual RRC connection isrequired, the second DRX (eDRX) UE may acquire the MIB and the SIB1,check the system information change related information(systemInfoValueTag information) included in the SIB 1 to identifywhether the system information is updated, and update the systeminformation.

FIG. 16A is a diagram illustrating a method for notifying changed systeminformation to UE according to a second embodiment of the presentinvention.

Referring to FIG. 16A, the UE that operates by applying the second DRX(eDRX) may perform paging monitoring only in a PHF 1611, based on ahyper SFN. In the PHF, the UE may receive paging in a PF and a POderived by applying typical or separate DRX parameters.

Meanwhile, system information (SI) update 1613 may occur in a timeinterval 1612 other than the PHF. If the updated SI is broadcasted fromthe (m+1)-th MP 1615, the eNB may send SI update notification 1616 tothe UEs in the m-th MP 1614 by using the paging.

However, the UE that applies the second DRX (eDRX) may not receive thepaging because of being not the PHF in the corresponding time, and maynot determine whether the SI is updated. Therefore, as described above,the eNB may operate differently depending on the type of the updated SI.

Specifically, when the first SI is updated, the eNB may transmit apaging message for notifying the first SI update in the extended MP.Specifically, during a certain period, e.g., the (m+x)-th MP 1617, inthe upcoming PHF 1611 after the SI update, the eNB may transmit thepaging 1618 for notifying the first SI update. At this time, the PF andPO 1619 in the PHF may be derived by applying typical or separate DRXparameters.

The first SI may include system information related to reception of thepaging message and to mobility. For example, the first SI may includecell access related information (CellAccessRelatedInfo), paging controlchannel configuration information (PCCH-config), cell list information(intraFreqNeighCellList), and the like.

The reason to update the first SI as soon as possible by using thepaging is that the UE being in an idle mode is related to the pagingreception and mobility that should maintain the newest information.

Besides, the UE may check the system information change relatedinformation (ValueTag information) included in the SIB 1 before actuallyattempting the RRC connection, and thereby determine whether the secondSI is updated. The second SI may include system information related tothe RRC connection configuration, for example, access barringconfiguration information (AC-BarringConfig), random access controlchannel configuration information (RACH-config), and the like. Thesecond SI need not maintain the newest information until the UE actuallyattempts the connection. Therefore, the eNB may notify the second SIupdate by using the SIB1 rather than using the paging.

The representative first SI is paging control channel configurationinformation (PCCH-config IE). This information may be included in theSIB2 and broadcasted.

The PCCH-config IE may include configuration information as shown inTable 1 below.

TABLE 1 PCCH-Config ::= SEQUENCE { 

defaultPagingCycle ENUMERATED { 

rf32, rf64, rf128, rf256), 

nB ENUMERATED { 

fourT, twoT, oneT, halfT, quarterT, oneEighthT, 

oneSixteenthT, oneThirtySecondT} 

} 

PCCH-Config-v1310 ::= SEQUENCE { 

paging-narrowBands-r13 INTEGER (1..maxAvailNarrowBands-r13), 

mpdcch-NumRepetition-Paging-r13 ENUMERATED {r1, r2, r4, r8, r16, r32,r64, r128, r256), 

nB-v1310 ENUMERATED {one64thT, one128thT, one256thT} 

OPTIONAL -- Need OR 

} 

The default paging cycle (defaultPagingCycle) may indicate a cellspecific paging cycle. The paging-related first parameter (nB) is avariable used to derive the paging frame (PF).

In addition, in the machine type communication (MTC) technology, the eNBmay repeatedly transmit a machine type physical downlink control channel(MPDCCH) for indicating paging and a paging message in a plurality ofnarrow bands, and related configuration information may be included inthe PCH-config.

The paging-narrowband may be used to indicate the narrowband used forthe paging, and the range of the paging-related first parameter (nBvalue) may be extended in consideration of repeated transmission.

Therefore, if a related cell supports the MTC, and if information ofPCCH-Config-v1310 IE is changed, the present invention is characterizedin that the eNB broadcasts a need of SI update by using the pagingmessage.

In addition, when the subframe bitmap related information(fdd-DownlinkOrTddSubframeBitmapLC-r13) and the hopping relatedinformation (si-HoppingConfigCommon-r13) included in the SIB1 arechanged, the present invention is characterized in that the eNBbroadcasts a need of SI update by using the paging message.

The fdd-DownlinkOrTddSubframeBitmapLC-r13 may include subframeinformation that can be used by the UE that applies the MTC technology.Since the paging message delivered to the MTC UE is transmitted only inthe subframe, this information is necessary for the UE to receive thepaging message.

The si-HoppingConfigCommon-r13 may indicate whether the SI message andthe paging message perform frequency hopping (frequency shift whentransmitting a message). If there is no such information, the UE willhave to perform blind decoding for all possible frequencies. Thus, thisinformation is necessary for the UE to receive the paging message.

bandwidthReducedAccessRelatedInfo-r13 SEQUENCE { 

si-WindowLength-BR-r13 ENUMERATED { 

ms20, ms40, ms60, ms80, ms120, 

ms160, ms200, spare}, 

si-RepetitionPattern-r13 ENUMERATED {everyRF, every2ndRF, every4thRF, 

every8thRF}, 

schedulingInfoList-BR-r13 SchedulingInfoList-BR-r13 OPTIONAL, -- NeedOR 

fdd-DownlinkOrTddSubframeBitmapLC-r13 CHOICE ( 

subframePattern10-r13 BIT STRING (SIZE (10)), 

subframePattern40-r13 BIT STRING (SIZE (40)) 

} OPTIONAL, -- Need OP 

fdd-UplinkSubframeBitmapLC-r13 BIT STRING (SIZE (10)) OPTIONAL, -- NeedOP 

startSymbolLC-r13 INTEGER (1..4), 

si-HoppingConfigCommon-r13 ENUMERATED {on, off}, 

si-ValidityTime-r13 ENUMERATED {true} OPTIONAL, -- Need OP 

systemInfoValueTagList-r13 SystemInfoValueTagList-r13 OPTIONAL -- NeedOR 

} OPTIONAL, -- Cond BW- reduced 

FIG. 16B is a diagram illustrating a modification period according tothe second embodiment of the present invention.

FIG. 16B is a diagram illustrating a method for extending themodification period (MP) so as to receive paging even when a very longDRX cycle is applied.

The MP may be extended so that at least one DRX timing is included inone MP 1621. That is, the MP 1621 may be set longer than the second DRXcycle 1620. In this case, the paging 1622 for SI change notification maybe transmitted at the paging occasion during the extended MP, and the UEmay receive it at least once 1623.

The MP value may be provided to the UE through SI (e.g., SIB2). Also,this MP may be operated separately from typical MP. Accordingly, whenthe MP is separately operated in the present invention, the typical MPmay be referred to as the first MP, and the extended MP may be referredto as the second MP.

FIG. 17 is a diagram illustrating a UE operation according to the secondembodiment of the present invention.

Referring to FIG. 17, at step S1705, the UE may be powered on, or thetracking area (TA) may be changed.

At step S1710, the UE may acquire system information from the eNB.

At step S1715, the UE that acquires the system information may identifywhether the system information includes the second DRX configurationinformation. That is, the UE may determine whether the systeminformation includes the second DRX-related first information and thepaging-related second parameter (the nB′ value).

Depending on cases described above, the second DRX configurationinformation (or the second DRX (eDRX) parameter value) included in theSIBx may be different. That is, in the case 1, the second DRX-relatedfirst information may be included. In the case 2, the second DRX-relatedfirst information and the paging-related second parameter (nB′) may beincluded. In the case 3, the second DRX-related first information, thepaging-related second parameter (nB′), and the paging-related thirdparameter (nB″) may be included.

If the second DRX-related first information and the paging-relatedsecond parameter (the nB′ value) are included in the system information,the UE may perform an RRC connection establishment process at stepS1720.

After the RRC connection is completed, the UE may transmit a requestmessage to the MME at step S1725. If the UE prefers to apply the secondDRX (eDRX) or if the UE supports the second DRX, the UE may include thefirst DRX-related second information (the UE specific DRX) and thesecond DRX-related second information (the UE specific eDRX value) inthe request message (the ATTACH REQUEST or TAU REQUEST message) andtransmit the request message to the MME. As described above, the firstDRX-related second information may include the first DRX cycleinformation preferred by the UE, and the second DRX-related secondinformation may include the second DRX cycle information preferred bythe UE. The cycle information preferred by the UE may mean cycleinformation determined to be applied by the UE.

In addition, at step S1730, the UE may receive a response message (e.g.,the ATTACH ACCEPT or TAU ACCEPT message) corresponding to the requestmessage from the MME.

At step S1735, the UE that receives the response message may determinewhether the second DRX-related third information (the allowed eDRXparameter) is included in the message. The second DRX-related thirdinformation (the allowed eDRX parameter) may include informationindicating whether the MME supports the second DRX (eDRX), or the secondDRX cycle information (the eDRX cycle information) having to be appliedby the UE.

When the response message includes the second DRX-related thirdinformation, the UE may perform an RRC connection release process atstep S1740.

At step S1745, the UE that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, at step S1750, the UE may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, at step S1755, the UE may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

In this case, the modification period (MP) may be extended so that thepaging message can be received even when a very long DRX cycle isapplied to the second DRX. The MP may be extended so that at least onesecond DRX timing is included in one MP, and the UE may receive thepaging at least once in the MP.

The paging message may include the second system information changeindicator which is an indicator for notifying an update of the firstsystem information.

If the paging message includes the second system information changeindicator, the UE may receive the first system information beingbroadcasted currently.

Thereafter, the UE may trigger the RRC connection at step S1760.

After the RRC connection is triggered, the UE may sequentially receivethe MIB and the system information (e.g., SIB1, SIBx) at step S1765.

At step S1770, the UE that receives the system information may identifythe system information change related information (systemInfoValueTag orsystemInfoValueTagExt value) in the SIB1.

At step S1775, the UE that identifies the system information changerelated information may determine whether the value of the identifiedinformation (IE) is different from the stored value.

If the identified information is not different from the informationstored in the UE, the UE does not need to update the second systeminformation.

On the other hand, the identified information is different from theinformation stored in the UE, the UE may receive at step S1780 thesecond system information being currently broadcasted by the eNB.

If the eNB does not broadcast the second DRX-related first informationand the paging-related second parameter (nB′) at step S1715, or if theMME does not transmit the second DRX-related third information (theallowed eDRX parameter) at step S1735, the UE may perform only the firstDRX (typical DRX) process at step S1780.

FIG. 18A is a diagram illustrating an eNB operation in the presentinvention.

Referring to FIG. 18A, at step S1810, the eNB may determine whether theeNB supports the second DRX (eDRX).

At step S1811, the eNB may broadcast system information (SI). If the eNBsupports the second DRX, the eNB may broadcast, to the UE, the SIincluding the second DRX-related first information and thepaging-related second parameter (nB′) as well as the first DRX-relatedfirst information and the paging-related first parameter which are thefirst DRX (typical DRX) configuration information.

Specifically, in the case 1, the second DRX-related first informationmay be included. In the case 2, the second DRX-related first informationand the paging-related second parameter (nB′) may be included. In thecase 3, the second DRX-related first information, the paging-relatedsecond parameter (nB′), and the paging-related third parameter (nB″) maybe included.

If the eNB does not support the second DRX, the eNB may broadcast the SIincluding only the first DRX (typical DRX) configuration information atstep S1812. If the eNB does not support the second DRX, the eNB mayoperate according to the first DRX as described with reference to FIG.4, and a detailed description will be omitted.

If the eNB supports the second DRX, the eNB may determine at step S1813whether the SI is updated.

If the SI is updated, the eNB may determine at step S1814 whether theupdated SI includes the first SI.

If the updated SI includes the first SI, the eNB may derive PHF, PF andPO at step S1815.

Thereafter, at step S1816, the eNB may transmit to the UE the pagingmessage indicating whether the SI is updated. The eNB may transmit thepaging message including the second SI change indicator indicatingwhether the SI is updated, based on the calculated PHF, PF and PO, tothe UEs that operate by applying the second DRX (eDRX). That is, the eNBmay transmit the paging message including the second SI change indicatorto the UE at the paging occasion (PO) within the modification period(MP).

Thereafter, at step S1817, the eNB may increase the systemInfoValueTagand the second SI change related information (systemInfoValueTagExt) byone. Alternatively, the eNB may increase the value of thesystemInfoValueTag by one and then, if wraparound occurs, increase thesystemInfoValueTagExt by one.

Also, even when the updated SI is not included in the first SI (i.e.,included in the second SI related to the RRC connection), the eNB mayincrease the values of the systemInfoValueTag and thesystemInfoValueTagExt included in the SI change related information byone. Alternatively, the eNB may increase the value of thesystemInfoValueTag by one and then, if wraparound occurs, increase thesystemInfoValueTagExt by one.

Thereafter, at step S1818, the eNB may broadcast the SI (e.g., SIB1)including the changed SI change related information (IE value). The eNBmay broadcast the updated SI from a specific time point (e.g., the timepoint when H-SFN mod 256=0).

FIG. 18B is a diagram illustrating another eNB operation in the presentinvention.

Referring to FIG. 18B, at step S1820, the eNB may determine to updatethe SI. At this time, the eNB may decide to update some or all of theSI.

At step S1821, the eNB may determine whether the eNB supports the secondDRX (extended DRX cycle).

If the eNB does not support the second DRX, the eNB may perform the SIupdate according to the first DRX (typical technology) at step S1822.

On the other hand, if the eNB supports the second DRX, the eNB maydetermine at step S1823 whether the service coverage extension functionis supported in the MTC technology.

If the eNB does not support the service coverage extension function inthe MTC technology, the eNB may determine at step S1824 whether thechanged SI includes at least paging control channel configurationinformation (PCCH-config).

If the changed SI includes the PCCH-config, the eNB may transmit at stepS1825 the paging message or PDCCH including the second SI changeindicator (or SI update indicator) to the UE in order to notify whetherthe SI is updated.

On the other hand, if the changed SI does not include the PCCH-config,the eNB may skip step S1825.

Thereafter, at step S1826, the eNB may broadcast the updated SI in thesecond DRX acquisition period. At this time, the eNB may broadcast theupdated SI at the time point when the H-SFN mod 256=0 is satisfied.

Meanwhile, if the eNB supports the service coverage extension functionin the MTC technology, the eNB may determine at step S1827 whether thechanged SI includes at least one of the paging channel configurationinformation (pcch-config), the subframe bitmap related information(fdd-DownlinkOrTddSubframeBitmapLC-r13), and the hopping relatedinformation (si-HoppingConfigCommon-r13).

If at least one of the above information is included in the changed SI,the eNB may transmit at step S1828 the paging message or (M)PDCCHincluding the second SI change indicator (or SI update indicator) to theUE in order to notify whether the SI is updated.

However, if at least one of the above information is not included in thechanged SI, the eNB may skip step S1828.

Thereafter, at step S1829, the eNB may broadcast the updated SI in thesecond DRX acquisition period. At this time, the eNB may broadcast theupdated SI at the time point when the H-SFN mod 256=0 is satisfied.

FIG. 19 illustrates a block configuration of UE according to the presentinvention.

Referring to FIG. 19, the UE may include a radio frequency (RF)processor 1910, a baseband processor 1920, a storage 1930, and acontroller 1940. The RF processor 1910 may perform a function, such asband conversion and amplification of a signal, for transmitting andreceiving the signal through a wireless channel. That is, the RFprocessor 1910 may up-convert a baseband signal provided from thebaseband processor 1920 into an RF band signal to transmit the RF bandsignal through an antenna, and also down-convert an RF band signalreceived through the antenna into a baseband signal. For example, the RFprocessor 810 may include a transmitter filter, a receiver filter, anamplifier, a mixer, an oscillator, a digital to analog converter (DAC),an analog to digital converter (ADC), and the like. Although the drawingshows only one antenna, the UE may have a plurality of antennas. Inaddition, the RF processor 810 may include a plurality of RF chains.Further, the RF processor 810 may perform beamforming. For thebeamforming, the RF processor 810 may adjust the phase and size ofsignals transmitted and received through a plurality of antennas orantenna elements. The baseband processor 1920 may perform a conversionfunction between a baseband signal and a bit stream in accordance with aphysical layer standard of the system. For example, in datatransmission, the baseband processor 1920 may create complex symbols byencoding and modulating transmission bit streams. Also, in datareception, the baseband processor 1920 may restore reception bit streamsby demodulating and decoding a baseband signal provided from the RFprocessor 1910. In case of complying with orthogonal frequency divisionmultiplexing (OFDM) scheme, in data transmission, the baseband processor1920 may generate complex symbols by encoding and modulatingtransmission bit streams, map the complex symbols to subcarriers, andconstruct OFDM symbols through an inverse fast Fourier transform (IFFT)operation and a cyclic prefix (CP) insertion. In addition, in datareception, the baseband processor 1920 may divide a baseband signalprovided from the RF processor 1910 into OFDM symbol units, restoresignals mapped to subcarriers through a fast Fourier transform (FFT)operation, and restore reception bit streams through demodulation anddecoding. The baseband processor 1920 and the RF processor 1910 maytransmit and receive a signal as described above. Accordingly, thebaseband processor 1920 and the RF processor 1910 may be referred to asa transmitting unit, a receiving unit, a transceiver, or a communicationunit. In addition, at least one of the baseband processor 1920 and theRF processor 1910 may include a plurality of communication modules tosupport a plurality of different wireless access technologies. Also, atleast one of the baseband processor 1920 and the RF processor 1910 mayinclude different communication modules for processing signals ofdifferent frequency bands. For example, the different wireless accesstechnologies may include a wireless LAN (e.g., IEEE 802.11), a cellularnetwork (e.g., LTE), and the like. In addition, the different frequencybands may include a super high frequency (SHF) band (e.g., 2.5 GHz, 5GHz), and a millimeter wave (e.g., 60 GHz) band. In addition, thestorage 1930 may store a basic program for the operation of the UE, anapplication program, and data such as setting information. Inparticular, the storage 1930 may store information associated with anaccess node that performs wireless communication by using a secondwireless access technology. Also, the storage 1930 may provide thestored data in response to a request of the controller 1940. Thecontroller 1940 may control overall operations of the UE. For example,the controller 1940 may transmit and receive a signal through thebaseband processor 1920 and the RF processor 1910. Also, the controller1940 writes and read data to and from the storage 1940. For this, thecontroller 1940 may include at least one processor. For example, thecontroller 1940 may include a communication processor (CP) for performthe control for communication and an application processor (AP) forcontrolling an upper layer such as an application program. According toan embodiment of the present invention, the controller 1940 may controlthe UE to perform the above-described operations and procedures of theUE.

Specifically, the controller 1940 may acquire system information fromthe eNB. The controller 1940 may identify whether the system informationincludes the second DRX configuration information. That is, the UE maydetermine whether the system information includes the second DRX-relatedfirst information and the paging-related second parameter (the nB′value).

Depending on cases described above, the second DRX configurationinformation (or the second DRX (eDRX) parameter value) included in theSIBx may be different. That is, in the case 1, the second DRX-relatedfirst information may be included. In the case 2, the second DRX-relatedfirst information and the paging-related second parameter (nB′) may beincluded. In the case 3, the second DRX-related first information, thepaging-related second parameter (nB′), and the paging-related thirdparameter (nB″) may be included.

The controller 1940 may perform an RRC connection establishment process.After the RRC connection is completed, the controller 1940 may transmita request message to the MME. If the UE prefers to apply the second DRX(eDRX) or if the UE supports the second DRX, the controller 1940 mayinclude the first DRX-related second information (the UE specific DRX)and the second DRX-related second information (the UE specific eDRXvalue) in the request message and transmit the request message to theMME.

In addition, the controller 1940 may receive a response messagecorresponding to the request message from the MME.

The controller 1940 that receives the response message may determinewhether the second DRX-related third information (the allowed eDRXparameter) is included in the message. The second DRX-related thirdinformation (the allowed eDRX parameter) may include informationindicating whether the MME supports the second DRX (eDRX), or the secondDRX cycle information (the eDRX cycle information) having to be appliedby the UE.

When the response message includes the second DRX-related thirdinformation, the controller 1940 may perform an RRC connection releaseprocess.

The controller 1940 that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, the controller 1940 may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, the controller 1940 may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

In this case, the modification period (MP) may be extended so that thepaging message can be received even when a very long DRX cycle isapplied to the second DRX. The MP may be extended so that at least onesecond DRX timing is included in one MP, and the UE may receive thepaging at least once in the MP.

The paging message may include the second system information changeindicator which is an indicator for notifying an update of the firstsystem information.

If the paging message includes the second system information changeindicator, the controller 1940 may receive the first system informationbeing broadcasted currently.

Thereafter, the controller 1940 may trigger the RRC connection.

After the RRC connection is triggered, the controller 1940 maysequentially receive the MIB and the system information (e.g., SIB1,SIBx).

The controller 1940 may identify the system information change relatedinformation (systemInfoValueTag or systemInfoValueTagExt value) in theSIB1.

The controller 1940 may determine whether the value of the identifiedinformation (IE) is different from the stored value.

If the identified information is not different from the informationstored in the UE, the controller 1940 does not need to update the secondsystem information.

On the other hand, the identified information is different from theinformation stored in the UE, the controller 1940 may receive the secondsystem information being currently broadcasted by the eNB.

If the eNB does not broadcast the second DRX-related first informationand the paging-related second parameter (nB′), or if the MME does nottransmit the second DRX-related third information (the allowed eDRXparameter), the controller 1940 may perform only the first DRX (typicalDRX) process.

FIG. 20 is a diagram illustrating a configuration of eNB according tothe present invention.

As shown in FIG. 20, the eNB may include an RF processor 2010, abaseband processor 2020, a backhaul communication unit 2030, a storage2040, and a controller 2050. The RF processor 2010 may perform afunction, such as band conversion and amplification of a signal, fortransmitting and receiving the signal through a wireless channel. Thatis, the RF processor 2010 may up-convert a baseband signal provided fromthe baseband processor 2020 into an RF band signal to transmit the RFband signal through an antenna, and also down-convert an RF band signalreceived through the antenna into a baseband signal. For example, the RFprocessor 2010 may include a transmitter filter, a receiver filter, anamplifier, a mixer, an oscillator, a DAC, an ADC, and the like. Althoughthe drawing shows only one antenna, the first access node may have aplurality of antennas. In addition, the RF processor 2010 may include aplurality of RF chains. Further, the RF processor 2010 may performbeamforming. For the beamforming, the RF processor 2010 may adjust thephase and size of signals transmitted and received through a pluralityof antennas or antenna elements. The baseband processor 2020 may performa conversion function between a baseband signal and a bit stream inaccordance with a physical layer standard of the first wireless accesstechnology. For example, in data transmission, the baseband processor2020 may create complex symbols by encoding and modulating transmissionbit streams. Also, in data reception, the baseband processor 2020 mayrestore reception bit streams by demodulating and decoding a basebandsignal provided from the RF processor 2010. In case of complying withOFDM scheme, in data transmission, the baseband processor 2020 maygenerate complex symbols by encoding and modulating transmission bitstreams, map the complex symbols to subcarriers, and construct OFDMsymbols through an IFFT operation and a CP insertion. In addition, indata reception, the baseband processor 2020 may divide a baseband signalprovided from the RF processor 2010 into OFDM symbol units, restoresignals mapped to subcarriers through an FFT operation, and restorereception bit streams through demodulation and decoding. The basebandprocessor 2020 and the RF processor 2010 may transmit and receive asignal as described above. Thus, the baseband processor 2020 and the RFprocessor 2010 may be referred to as a transmitting unit, a receivingunit, a transceiver, a communication unit, or a wireless communicationunit. The backhaul communication unit 2030 may provide an interface forperforming communication with other node in the network. That is, thebackhaul communication unit 2030 may convert a bit stream transmittedfrom the main eNB to another node, e.g., a sub-eNB, a core network,etc., into a physical signal, and may also convert a physical signalreceived from such other node into a bit stream. The storage 2040 maystore a basic program for the operation of the main eNB, an applicationprogram, and data such as setting information. In particular, thestorage 2040 may store information on a bearer allocated to connectedUE, a measurement result reported from the connected UE, and the like.In addition, the storage 2040 may store information for determiningwhether to provide or suspend multiple connections to or from the UE.Also, the storage 2040 may provide the stored data in response to arequest of the controller 2050. The controller 2050 may control overalloperations of the main eNB. For example, the controller 2050 maytransmit and receive a signal through the baseband processor 2020 andthe RF processor 2010 or through the backhaul communication unit 2030.Also, the controller 2050 writes and read data to and from the storage2040. For this, the controller 2050 may include at least one processor.According to an embodiment of the present invention, the controller 2050may include a multi-connection controller 2052 for performing controlfor providing multiple connections to the UE. For example, thecontroller 2050 may control the eNB to perform the above-describedoperations and procedures.

Specifically, the controller 2050 may determine whether the eNB supportsthe second DRX (eDRX).

The controller 2050 may broadcast system information (SI). If the eNBsupports the second DRX, the controller 2050 may broadcast, to the UE,the SI including the second DRX-related first information and thepaging-related second parameter (nB′) as well as the first DRX-relatedfirst information and the paging-related first parameter which are thefirst DRX (typical DRX) configuration information.

Specifically, in the case 1, the second DRX-related first informationmay be included. In the case 2, the second DRX-related first informationand the paging-related second parameter (nB′) may be included. In thecase 3, the second DRX-related first information, the paging-relatedsecond parameter (nB′), and the paging-related third parameter (nB″) maybe included.

If the eNB does not support the second DRX, the controller 2050 maybroadcast the SI including only the first DRX (typical DRX)configuration information.

If the eNB supports the second DRX, the controller 2050 may determinewhether the SI is updated.

If the SI is updated, the controller 2050 may determine whether theupdated SI includes the first SI.

If the updated SI includes the first SI, the controller 2050 may derivePHF, PF and PO.

Thereafter, the controller 2050 may transmit to the UE the pagingmessage indicating whether the SI is updated. The controller 2050 maytransmit the paging message including the second SI change indicatorindicating whether the SI is updated, based on the calculated PHF, PFand PO, to the UEs that operate by applying the second DRX (eDRX).

Thereafter, the controller 2050 may increase the systemInfoValueTag andthe second SI change related information (systemInfoValueTagExt) by one.Alternatively, the controller 2050 may increase the value of thesystemInfoValueTag by one and then, if wraparound occurs, increase thesystemInfoValueTagExt by one.

Also, even when the updated SI is not included in the first SI (i.e.,included in the second SI related to the RRC connection), the controller2050 may increase the values of the systemInfoValueTag and thesystemInfoValueTagExt included in the SI change related information byone. Alternatively, the controller 2050 may increase the value of thesystemInfoValueTag by one and then, if wraparound occurs, increase thesystemInfoValueTagExt by one.

Thereafter, the controller 2050 may broadcast the SI (e.g., SIB1)including the changed SI change related information (IE value). Thecontroller 2050 may broadcast the updated SI from a specific time point(e.g., the time point when H-SFN mod 256=0).

In addition, the controller 2050 may determine to update the SI. At thistime, the controller 2050 may decide to update some or all of the SI.

The controller 2050 may determine whether the eNB supports the secondDRX.

If the eNB does not support the second DRX, the controller 2050 mayperform the SI update according to the first DRX.

On the other hand, if the eNB supports the second DRX, the controller2050 may determine whether the service coverage extension function issupported in the MTC technology.

If the eNB does not support the service coverage extension function inthe MTC technology, the controller 2050 may determine whether thechanged SI includes at least paging control channel configurationinformation (PCCH-config).

If the changed SI includes the PCCH-config, the controller 2050 maytransmit the paging message or PDCCH including the second SI changeindicator (or SI update indicator) to the UE in order to notify whetherthe SI is updated.

On the other hand, if the changed SI does not include the PCCH-config,the controller 2050 may skip a process of transmitting the second SIchange indicator.

Thereafter, the controller 2050 may broadcast the updated SI in thesecond DRX acquisition period. At this time, the controller 2050 maybroadcast the updated SI at the time point when the H-SFN mod 256=0 issatisfied.

Meanwhile, if the eNB supports the service coverage extension functionin the MTC technology, the controller 2050 may determine whether thechanged SI includes at least one of the paging channel configurationinformation (pcch-config), the subframe bitmap related information(fdd-DownlinkOrTddSubframeBitmapLC-r13), and the hopping relatedinformation (si-HoppingConfigCommon-r13).

If at least one of the above information is included in the changed SI,the controller 2050 may transmit the paging message or (M)PDCCHincluding the second SI change indicator (or SI update indicator) to theUE in order to notify whether the SI is updated.

However, if at least one of the above information is not included in thechanged SI, the controller 2050 may skip the above process.

Thereafter, the controller 2050 may broadcast the updated SI in thesecond DRX acquisition period. At this time, the controller 2050 maybroadcast the updated SI at the time point when the H-SFN mod 256=0 issatisfied.

Third Embodiment

The present invention proposes another method for determining whetherthe system information (SI) is updated, when the DRX cycle is set to belonger than the modification period (MP) in order to reduce powerconsumption.

When the SI is updated, the eNB should notify the SI update to all UEsthat are in the idle mode. As described above, this is performed througha paging message. Since the eNB does not know which idle-mode UE existsin its area, the eNB may transmit the paging message through allpossible POs during the MP. The MP may be an integer multiple of thefirst DRX cycle (the default DRX cycle).

On the other hand, in the second DRX (eDRX), the length of the secondDRX cycle (the DRX cycle) may reach several tens of minutes. One ofmethods for notifying whether the SI is updated, for the UE that appliesthe second DRX (eDRX), is a method for continuously transmitting thepaging message throughout the second DRX cycle (the DRX cycle).

Alternatively, since the SI update method applied to the normal DRX UEis a pre-notification, the UE may perform SI refresh or SI reacquisitionin the next MP when recognizing the occurrence of the SI update.Therefore, the present invention is characterized in that the eNBtransmits the paging message only in some HFs after the SI update occursfor the second DRX (eDRX) UE. That is, because of a post-notification,the UE may immediately perform SI reacquisition (SI refresh) whenrecognizing the occurrence of the SI update.

Specifically, when the SI is updated in the MP [m+1], the eNB maytransmit the paging message through all available POs of all availablePFs in the MP [m] for the first DRX (typical DRX) UE.

In addition, for the second DRX (eDRX) UE, the eNB may transmit thepaging message through all available POs of all available PFs of allavailable PHFs during a certain period after the MP [m+1]. The pagingmessage may include the second SI change indicator(systemInfoModification2) and system change related information (valuetag).

The reason that the second SI change indicator (systemInfoModication2)is introduced is to instruct the UE to reacquire the SI from the momentthat the UE receives the paging message. As described above, the UE thatreceives the first SI change indicator (typical systemInfoModification)may reacquire the SI from the next MP.

In the present invention, SI change related information (value tag) maybe included in the paging message. This reason is to prevent the UE,which has already acquired the updated SI, from unnecessarilyreacquiring the same SI by receiving the paging message.

In this case, DRX parameters (configurable parameter) may be introducedto control the number of available PHFs, available PFs, and availablePOs. In the DRX parameters, the parameter for the first DRX (typicalDRX) and the parameter for the second DRX (eDRX) may be configuredindependently. Therefore, the PF and PO for the first DRX (typical DRX)and the PF and PO for the second DRX (eDRX) may be configured indifferent radio frames or subframes.

A method for configuring the DRX parameters is the same as theabove-described methods (Case 1, 2, and 3), and a detailed descriptionwill be omitted.

FIG. 21 is a diagram illustrating a method for notifying changed systeminformation to UE according to a third embodiment of the presentinvention.

Referring to FIG. 21, the UE that applies the second DRX (eDRX) mayperform paging monitoring only in a PHF 2111, based on a hyper SFN. Inthe PHF, the UE may receive paging in a PF and a PO derived by applyingtypical or separate DRX parameters.

Meanwhile, system information (SI) update 2113 may occur in a timeinterval 2112 other than the PHF. If the updated SI is broadcasted fromthe (m+1)-th MP 2115, the eNB may send SI update notification 2116 tothe UEs in the m-th MP 2114 by using the paging.

However, the UE that applies the second DRX (eDRX) may not receive thepaging because of being not the PHF in the corresponding time, and maynot determine whether the SI is updated. In order to this, the eNB maytransmit the paging 2118 for notifying the SI update during a certainperiod, e.g., the (m+x)-th MP 2117, in the upcoming PHF 2111 after theSI update. At this time, the PF and PO 2119 in the PHF may be derived byapplying typical or separate DRX parameters.

FIG. 22 is a diagram illustrating a UE operation according to the thirdembodiment of the present invention.

Referring to FIG. 22, at step S2205, the UE may be powered on, or thetracking area (TA) may be changed.

At step S2210, the UE may acquire system information from the eNB.

At step S2215, the UE that acquires the system information may identifywhether the system information includes the second DRX configurationinformation (or the second DRX parameter). Specifically, the UE maydetermine whether the system information includes the second DRX-relatedfirst information and the paging-related second parameter (the nB′value).

Depending on cases described above, the second DRX (eDRX) parametervalue included in the SIBx may be different. That is, in the case 1, thesecond DRX-related first information may be included. In the case 2, thesecond DRX-related first information and the paging-related secondparameter (nB′) may be included. In the case 3, the second DRX-relatedfirst information, the paging-related second parameter (nB′), and thepaging-related third parameter (nB″) may be included.

If the second DRX-related first information and the paging-relatedsecond parameter (the nB′ value) are included in the system information,the UE may perform an RRC connection establishment process at stepS2220.

After the RRC connection is completed, the UE may transmit a requestmessage to the MME at step S2225. If the UE prefers to apply the secondDRX (eDRX) or if the UE supports the second DRX, the UE may include thefirst DRX-related second information (the UE specific DRX) and thesecond DRX-related second information (the UE specific eDRX value) inthe request message (the ATTACH REQUEST or TAU REQUEST message) andtransmit the request message to the MME. As described above, the firstDRX-related second information may include the first DRX cycleinformation preferred by the UE, and the second DRX-related secondinformation may include the second DRX cycle information preferred bythe UE. The cycle information preferred by the UE may mean cycleinformation determined to be applied by the UE.

In addition, at step S2230, the UE may receive a response message (e.g.,the ATTACH ACCEPT or TAU ACCEPT message) corresponding to the requestmessage from the MME.

At step S2235, the UE that receives the response message may determinewhether the second DRX-related third information (the allowed eDRXparameter) is included in the message. The second DRX-related thirdinformation (the allowed eDRX parameter) may include informationindicating whether the MME supports the second DRX (eDRX), or the secondDRX (eDRX) cycle information having to be applied by the UE.

When the response message includes the second DRX-related thirdinformation, the UE may perform an RRC connection release process atstep S2240.

At step S2245, the UE that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, at step S2250, the UE may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, at step S2255, the UE may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

If the first system information change indicator(SystemInfoModification) is included in the paging message, the UE mayreceive the system information from the start time point of the nextmodification period (MP). If the second system information changeindicator (SystemInfoModification2) is included in the paging message,and if the system information change related information (value tag) isdifferent from the stored value, the UE may receive the systeminformation from the start time point of the next repetition period orfrom the time point of receiving the paging message. If the secondsystem information change indicator (SystemInfoModification2) iscontained in the paging message, and if the system information changerelated information (value tag) is identical with the stored value, theUE may not reacquire the system information.

Meanwhile, if the eNB does not broadcast the second DRX-related firstinformation and the paging-related second parameter (nB′) at step S2215,or if the MME does not transmit the second DRX-related third information(the allowed eDRX parameter) at step S2235, the UE may perform only thefirst DRX (typical DRX) process at step S2260.

FIG. 23 is a diagram illustrating an eNB operation according to thethird embodiment of the present invention.

Referring to FIG. 23, at step S2310, the eNB may determine whether theeNB supports the second DRX (eDRX).

At step S2320, the eNB may broadcast system information (SI). If the eNBsupports the second DRX, the eNB may broadcast, to the UE, the SIincluding the second DRX-related first information and thepaging-related second parameter (nB′) as well as the first DRX-relatedfirst information and the paging-related first parameter which are thefirst DRX (typical DRX) configuration information.

Specifically, in the case 1, the second DRX-related first informationmay be included. In the case 2, the second DRX-related first informationand the paging-related second parameter (nB′) may be included. In thecase 3, the second DRX-related first information, the paging-relatedsecond parameter (nB′), and the paging-related third parameter (nB″) maybe included.

If the eNB does not support the second DRX, the eNB may broadcast the SIincluding only the first DRX (typical DRX) configuration information atstep S2330. If the eNB does not support the second DRX, the eNB mayoperate according to the first DRX as described with reference to FIG.4, and a detailed description will be omitted.

In addition, at step S2340, the SI may be updated. When the SI isupdated, the eNB may derive PHF, PF and PO at step S2350.

Thereafter, at step S2360, the eNB may transmit to the UE the pagingmessage indicating whether the SI is updated. The eNB may transmit thepaging message including the second SI change indicator indicatingwhether the SI is updated, based on the calculated PHF, PF and PO, tothe UEs that operate by applying the second DRX (eDRX). The eNB mayinclude the second SI change indicator (SystemInfoModification2) and theSI change related information (value tag) in the paging message.

FIG. 24 illustrates a block configuration of UE according to the thirdembodiment of the present invention.

Referring to FIG. 24, the UE may include a radio frequency (RF)processor 2410, a baseband processor 2420, a storage 2430, and acontroller 2440.

The RF processor 2410 may perform a function, such as band conversionand amplification of a signal, for transmitting and receiving the signalthrough a wireless channel. That is, the RF processor 2410 mayup-convert a baseband signal provided from the baseband processor 2420into an RF band signal to transmit the RF band signal through anantenna, and also down-convert an RF band signal received through theantenna into a baseband signal. For example, the RF processor 2410 mayinclude a transmitter filter, a receiver filter, an amplifier, a mixer,an oscillator, a digital to analog converter (DAC), an analog to digitalconverter (ADC), and the like. Although the drawing shows only oneantenna, the UE may have a plurality of antennas. In addition, the RFprocessor 2410 may include a plurality of RF chains. Further, the RFprocessor 2410 may perform beamforming. For the beamforming, the RFprocessor 2410 may adjust the phase and size of signals transmitted andreceived through a plurality of antennas or antenna elements.

The baseband processor 2420 may perform a conversion function between abaseband signal and a bit stream in accordance with a physical layerstandard of the system. For example, in data transmission, the basebandprocessor 2420 may create complex symbols by encoding and modulatingtransmission bit streams. Also, in data reception, the basebandprocessor 2420 may restore reception bit streams by demodulating anddecoding a baseband signal provided from the RF processor 2410. In caseof complying with orthogonal frequency division multiplexing (OFDM)scheme, in data transmission, the baseband processor 2420 may generatecomplex symbols by encoding and modulating transmission bit streams, mapthe complex symbols to subcarriers, and construct OFDM symbols throughan inverse fast Fourier transform (IFFT) operation and a cyclic prefix(CP) insertion. In addition, in data reception, the baseband processor2420 may divide a baseband signal provided from the RF processor 2410into OFDM symbol units, restore signals mapped to subcarriers through afast Fourier transform (FFT) operation, and restore reception bitstreams through demodulation and decoding.

The baseband processor 2420 and the RF processor 2410 may transmit andreceive a signal as described above. Accordingly, the baseband processor2420 and the RF processor 2410 may be referred to as a transmittingunit, a receiving unit, a transceiver, or a communication unit. Inaddition, at least one of the baseband processor 2420 and the RFprocessor 2410 may include a plurality of communication modules tosupport a plurality of different wireless access technologies. Also, atleast one of the baseband processor 2420 and the RF processor 2410 mayinclude different communication modules for processing signals ofdifferent frequency bands. For example, the different wireless accesstechnologies may include a wireless LAN (e.g., IEEE 802.11), a cellularnetwork (e.g., LTE), and the like. In addition, the different frequencybands may include a super high frequency (SHF) band (e.g., 2.5 GHz, 5GHz), and a millimeter wave (e.g., 60 GHz) band.

The storage 2430 may store a basic program for the operation of the UE,an application program, and data such as setting information. Inparticular, the storage 2430 may store information associated with asecond access node that performs wireless communication by using asecond wireless access technology. Also, the storage 2430 may providethe stored data in response to a request of the controller 2440.

The controller 2440 may control overall operations of the UE. Forexample, the controller 2440 may transmit and receive a signal throughthe baseband processor 2420 and the RF processor 2410. Also, thecontroller 2440 writes and read data to and from the storage 2440. Forthis, the controller 2440 may include at least one processor. Forexample, the controller 2440 may include a communication processor (CP)for perform the control for communication and an application processor(AP) for controlling an upper layer such as an application program.According to an embodiment of the present invention, the controller 2440may control the UE to perform the above-described operations andprocedures of the UE.

Specifically, the controller 2440 may acquire system information fromthe eNB.

The controller 2440 that acquires the system information may identifywhether the system information includes the second DRX configurationinformation (or the second DRX parameter). Specifically, the controller2440 may determine whether the system information includes the secondDRX-related first information and the paging-related second parameter(the nB′ value).

Depending on cases described above, the second DRX (eDRX) parametervalue included in the SIBx may be different. That is, in the case 1, thesecond DRX-related first information may be included. In the case 2, thesecond DRX-related first information and the paging-related secondparameter (nB′) may be included. In the case 3, the second DRX-relatedfirst information, the paging-related second parameter (nB′), and thepaging-related third parameter (nB″) may be included.

The controller 2440 may perform an RRC connection establishment process.After the RRC connection is completed, the controller 2440 may transmita request message to the MME. If the UE prefers to apply the second DRX(eDRX) or if the UE supports the second DRX, the controller 2440 mayinclude the first DRX-related second information (the UE specific DRX)and the second DRX-related second information (the UE specific eDRXvalue) in the request message and transmit the request message to theMME.

In addition, the controller 2440 may receive a response messagecorresponding to the request message from the MME.

The controller 2440 may determine whether the second DRX-related thirdinformation (the allowed eDRX parameter) is included in the responsemessage. The second DRX-related third information (the allowed eDRXparameter) may include information indicating whether the MME supportsthe second DRX (eDRX), or the second DRX (eDRX) cycle information havingto be applied by the UE.

When the response message includes the second DRX-related thirdinformation, the controller 2440 may perform an RRC connection releaseprocess.

The controller 2440 that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, the controller 2440 may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, the controller 2440 may attempt to receive the pagingmessage thereof at the paging reception timing indicated by thedetermined PHF and PF.

If the first system information change indicator(SystemInfoModification) is included in the paging message, thecontroller 2440 may receive the system information from the start timepoint of the next modification period (MP). If the second systeminformation change indicator (SystemInfoModification2) is included inthe paging message, and if the system information change relatedinformation (value tag) is different from the stored value, thecontroller 2440 may receive the system information from the start timepoint of the next repetition period or from the time point of receivingthe paging message. If the second system information change indicator(SystemInfoModification2) is contained in the paging message, and if thesystem information change related information (value tag) is identicalwith the stored value, the controller 2440 may not reacquire the systeminformation.

Meanwhile, if the eNB does not broadcast the second DRX-related firstinformation and the paging-related second parameter (nB′), or if the MMEdoes not transmit the second DRX-related third information (the allowedeDRX parameter), the controller 2440 may perform only the first DRX(typical DRX) process.

FIG. 25 illustrates a block configuration of eNB according to the thirdembodiment of the present invention.

As shown in FIG. 25, the eNB may include an RF processor 2510, abaseband processor 2520, a backhaul communication unit 2530, a storage2540, and a controller 2550.

The RF processor 2510 may perform a function, such as band conversionand amplification of a signal, for transmitting and receiving the signalthrough a wireless channel. That is, the RF processor 2510 mayup-convert a baseband signal provided from the baseband processor 2520into an RF band signal to transmit the RF band signal through anantenna, and also down-convert an RF band signal received through theantenna into a baseband signal. For example, the RF processor 2510 mayinclude a transmitter filter, a receiver filter, an amplifier, a mixer,an oscillator, a DAC, an ADC, and the like. Although the drawing showsonly one antenna, the first access node may have a plurality ofantennas. In addition, the RF processor 2510 may include a plurality ofRF chains. Further, the RF processor 2510 may perform beamforming. Forthe beamforming, the RF processor 2510 may adjust the phase and size ofsignals transmitted and received through a plurality of antennas orantenna elements.

The baseband processor 2520 may perform a conversion function between abaseband signal and a bit stream in accordance with a physical layerstandard of the first wireless access technology. For example, in datatransmission, the baseband processor 2520 may create complex symbols byencoding and modulating transmission bit streams. Also, in datareception, the baseband processor 2520 may restore reception bit streamsby demodulating and decoding a baseband signal provided from the RFprocessor 2510. In case of complying with OFDM scheme, in datatransmission, the baseband processor 2520 may generate complex symbolsby encoding and modulating transmission bit streams, map the complexsymbols to subcarriers, and construct OFDM symbols through an IFFToperation and a CP insertion. In addition, in data reception, thebaseband processor 2520 may divide a baseband signal provided from theRF processor 2510 into OFDM symbol units, restore signals mapped tosubcarriers through an FFT operation, and restore reception bit streamsthrough demodulation and decoding. The baseband processor 2520 and theRF processor 2510 may transmit and receive a signal as described above.Thus, the baseband processor 2520 and the RF processor 2510 may bereferred to as a transmitting unit, a receiving unit, a transceiver, acommunication unit, or a wireless communication unit.

The backhaul communication unit 2530 may provide an interface forperforming communication with other node in the network. That is, thebackhaul communication unit 2530 may convert a bit stream transmittedfrom the main eNB to another node, e.g., a sub-eNB, a core network,etc., into a physical signal, and may also convert a physical signalreceived from such other node into a bit stream.

The storage 2540 may store a basic program for the operation of the maineNB, an application program, and data such as setting information. Inparticular, the storage 2540 may store information on a bearer allocatedto connected UE, a measurement result reported from the connected UE,and the like. In addition, the storage 2540 may store information fordetermining whether to provide or suspend multiple connections to orfrom the UE. Also, the storage 2540 may provide the stored data inresponse to a request of the controller 2550.

The controller 2550 may control overall operations of the main eNB. Forexample, the controller 2550 may transmit and receive a signal throughthe baseband processor 2520 and the RF processor 2510 or through thebackhaul communication unit 2530. Also, the controller 2550 writes andread data to and from the storage 2540. For this, the controller 2550may include at least one processor. According to an embodiment of thepresent invention, the controller 2550 may include a multi-connectioncontroller 2552 for performing control for providing multipleconnections to the UE. For example, the controller 2550 may control theeNB to perform the above-described operations and procedures.

Specifically, the controller 2550 may determine whether the eNB supportsthe second DRX (eDRX).

The controller 2550 may broadcast system information (SI). If the eNBsupports the second DRX, the controller 2550 may broadcast, to the UE,the SI including the second DRX-related first information and thepaging-related second parameter (nB′) as well as the first DRX-relatedfirst information and the paging-related first parameter which are thefirst DRX (typical DRX) configuration information.

Specifically, in the case 1, the second DRX-related first informationmay be included. In the case 2, the second DRX-related first informationand the paging-related second parameter (nB′) may be included. In thecase 3, the second DRX-related first information, the paging-relatedsecond parameter (nB′), and the paging-related third parameter (nB″) maybe included.

If the eNB does not support the second DRX, the controller 2550 maybroadcast the SI including only the first DRX (typical DRX)configuration information.

In addition, when the SI is updated, the controller 2550 may derive PHF,PF and PO.

Thereafter, the controller 2550 may transmit to the UE the pagingmessage indicating whether the SI is updated. The eNB may transmit thepaging message including the second SI change indicator indicatingwhether the SI is updated, based on the calculated PHF, PF and PO, tothe UEs that operate by applying the second DRX (eDRX). The eNB mayinclude the second SI change indicator (SystemInfoModification2) and theSI change related information (value tag) in the paging message.

Fourth Embodiment

The present invention proposes still another method for determiningwhether the system information (SI) is updated, when the DRX cycle isset to be longer than the modification period (MP) in order to reducepower consumption.

When the SI is updated, the eNB should notify the SI update to all UEsthat are in the idle mode. As described above, this is performed througha paging message. Since the eNB does not know which idle-mode UE existsin its area, the eNB may transmit the paging message through allpossible POs during the MP. The MP may be an integer multiple of thefirst DRX cycle (the default DRX cycle).

On the other hand, in the second DRX (eDRX), the length of the secondDRX cycle (the DRX cycle) may reach several tens of minutes. Since theSI update method applied to the normal DRX UE is a pre-notification, theUE may perform SI reacquisition (SI refresh) in the next MP whenrecognizing the occurrence of the SI update. Therefore, the presentinvention is characterized in that, for the second DRX (eDRX) UE, theeNB checks whether the SI is updated, by identifying the SI (e.g., SIB1)in some HFs after the SI update occurs. That is, because of apost-notification, the UE may immediately perform SI reacquisition (SIrefresh) when recognizing the occurrence of the SI update.

Specifically, when the SI is updated in the MP [m+1], the eNB maytransmit the paging message through all available POs of all availablePFs in the MP [m] for the first DRX (typical DRX) UE.

However, a separate paging message for the second DRX (eDRX) UE is nottransmitted. Instead, the second DRX (eDRX) UE may acquire the MIB andthe system information (SIB1) for each PHF and thereby identify systeminformation change related information (systemInfoValueTag information)in the SIB1. An exact time point may be as follows.

Scheme 1: Acquire the first MIB and SIB1 in the PHF

Scheme 2: Acquire the MIB and SIB1 closest to the first PF and PO in thePHF

FIG. 26 is a diagram illustrating a method for notifying changed systeminformation to UE according to a fourth embodiment of the presentinvention.

Referring to FIG. 26, the UE that applies the second DRX (eDRX) mayperform paging monitoring only in a PHF 2611, based on a hyper SFN. Inthe PHF, the UE may receive paging in a PF and a PO derived by applyingtypical or separate DRX parameters.

Meanwhile, system information (SI) update 2613 may occur in a timeinterval 2612 other than the PHF. If the updated SI is broadcasted fromthe (m+1)-th MP 2615, the eNB may send SI update notification 2616 tothe UEs in the m-th MP 2614 by using the paging.

However, the UE that applies the second DRX (eDRX) may not receive thepaging because of being not the PHF in the corresponding time, and maynot determine whether the SI is updated.

In order to this, the eNB may sequentially receive the MIB and the SIB1in the upcoming PHF 2111 after the SI update, and check whether the SIchange related information (systemInfoValueTag value) is identical withthe value 2617 stored by the UE. At this time, if the SI change relatedinformation (systemInfoValueTag value) included in the newly receivedSIB1 is not identical with the stored value, the UE may regard the SIupdate as occurring in a period other than the PHF and then update withthe SI being currently broadcasted.

The SI related information (systemInfoValueTag) may be reused by thesecond DRX (eDRX) UE, and a new systemInfoValueTagExt for the eDRX UEmay be defined separately. The systemInfoValueTag has a value of integer(0, . . . , 31) (That is, it has a value from 0 to 31 and may beincreased by 1 for each SI update. In case of exceeding 31, it mayreturn to 0.), and the systemInfoValueTagExt may have a value of integer(0, . . . , 256). This is because the second DRX (eDRX) may have a verylong DRX cycle during which the SI update may occur frequently.

Whenever the SI update occurs, the systemInfoValueTagExt may beincreased by one. Alternatively, the systemInfoValueTag value may bereused, and, in case of wraparound of the above value, thesystemInfoValueTagExt value may be increased by one. In this method, thesystemInfoValueTagExt value may be set to a lower value than that in theprevious method, such as integer (0, . . . , 15).

If the SI update occurs during the PHF, an indicator for indicating thismay be included in the paging message for the second DRX (eDRX) UE, andan update of new SI may be performed from the next MP as in a typicalmanner.

FIG. 27 is a diagram illustrating a UE operation according to the fourthembodiment of the present invention.

Referring to FIG. 27, at step S2705, the UE may be powered on, or thetracking area (TA) may be changed.

At step S2710, the UE may acquire system information from the eNB.

At step S2715, the UE that acquires the system information may identifywhether the system information includes the second DRX configurationinformation. Specifically, the UE may determine whether the systeminformation includes the second DRX-related first information and thepaging-related second parameter (the nB′ value).

If the second DRX-related first information and the paging-relatedsecond parameter (the nB′ value) are included in the system information,the UE may perform an RRC connection establishment process at stepS2720.

After the RRC connection is completed, the UE may transmit a requestmessage to the MME at step S2225. If the UE prefers to apply the secondDRX (eDRX) or if the UE supports the second DRX, the UE may include thefirst DRX-related second information (the UE specific DRX) and thesecond DRX-related second information (the UE specific eDRX value) inthe request message (the ATTACH REQUEST or TAU REQUEST message) andtransmit the request message to the MME. As described above, the firstDRX-related second information may include the first DRX cycleinformation preferred by the UE, and the second DRX-related secondinformation may include the second DRX cycle information preferred bythe UE. The cycle information preferred by the UE may mean cycleinformation determined to be applied by the UE.

In addition, at step S2730, the UE may receive a response message (e.g.,the ATTACH ACCEPT or TAU ACCEPT message) corresponding to the requestmessage from the MME.

At step S2735, the UE that receives the response message may determinewhether the second DRX-related third information (the allowed eDRXparameter) is included in the message. The second DRX-related thirdinformation (the allowed eDRX parameter) may include informationindicating whether the MME supports the second DRX (eDRX), or the secondDRX (eDRX) cycle information having to be applied by the UE.

When the response message includes the second DRX-related thirdinformation, the UE may perform an RRC connection release process atstep S2740.

At step S2745, the UE that releases the RRC connection may operate byapplying the second DRX (eDRX).

For this, at step S2750, the UE may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, when the calculated PHF arrives, the UE may sequentiallyreceive the MIB and SIB1 at step S2755.

At step S2760, the UE that receives the system information may identifythe systemInfoValueTag or systemInfoValueTagExt value included in theSIB1. The second DRX (eDRX) UE may receive the SIB1 at least once everyT′, which is the second DRX (eDRX) cycle, and then identify thesystemInfoValueTag or systemInfoValueTagExt. In performing the DRXoperation according to the second DRX (eDRX) cycle, the UE may receivethe SIB1 closest to the first PF and PO of the PHF determined accordingto the second DRX (eDRX) cycle in the time domain. Alternatively, the UEmay receive the closest SIB1 among SIB1s occurring after (or before) thefirst PF and PO of the PHF.

Thereafter, at step S2765, the UE may determine whether the identifiedvalue (of the IEs) and the stored value are different from each other.

If there is no difference, the UE does not need to update the systeminformation.

On the other hand, if the stored value differs from the identifiedvalue, the UE may receive at step S2770 the system information beingcurrently broadcasted by the eNB.

Meanwhile, if the eNB does not broadcast the second DRX-related firstinformation and the paging-related second parameter (nB′) at step S2705,or if the MME does not transmit the second DRX-related third information(the allowed eDRX parameter) at step S2235, the UE may perform only thefirst DRX (typical DRX) process at step S2775.

Although FIG. 27 relates the UE which is in the idle mode, the aboveoperation may be similarly applied to the UE which is in a connectedstate. The connected UE may also operate with DRX, and a long DRX cycleand a short DRX cycle may be set in the UE. The UE may apply the shortDRX cycle during data transmission and reception and apply the long DRXcycle during no data transmission and reception.

The long DRX cycle may be set from 10 ms to 10.24 sec, and be longerthan the modification period. The connected UE may perform system (SIB1)checking, as follows.

The UE may establish an RRC connection with the eNB, and notify the eNBwhether the second DRX (eDRX) is supported.

The eNB may set a long DRX cycle such as 10.24 seconds to the UE thatsupports the second DRX (eDRX).

The UE performs the first operation or the second operation, based onthe length of the set DRX cycle.

If the length of the set long DRX cycle is smaller than the first value,the UE may perform the first operation. If the length is greater thanthe first value, the UE may perform the second operation. The firstvalue may be a fixed value, for example, 2.56 seconds, or may be aspecific value set for each cell, for example, the length of amodification period.

The first operation is as follows. The UE may identify systeminformation (SIB1) at least once every modification period and therebydetermine whether the SI is changed. The UE may determine whether the SIis changed, by identifying the first system information (SIB1) of themodification period. If it is determined that the SI is changed, namely,if the value tag is different from the stored value, the UE may receiveSIBs again and replace the currently stored values with them.

The second operation is as follows. The UE may identify systeminformation (SIB1) at least once every cycle, which is a longer valuebetween the modification period and the long DRX cycle, and determinewhether the SI is changed. In case of identifying the system information(SIB1) at intervals of the long DRX cycle, the UE may identify thesystem information (SIB1) closest in time to onDuration. If it isdetermined that the SI is changed, namely, if the value tag is differentfrom the stored value, the UE may receive SIBs again and replace thecurrently stored values with them.

FIG. 28 is a diagram illustrating an eNB operation in the presentinvention.

Referring to FIG. 28, at step S2810, the eNB may determine whethersystem information is updated.

If the system information is updated, the eNB may increasesystemInfoValueTag and systemInfoValueTagExt by one at step S2820.Alternatively, the value of systemInfoValueTag may be increased by one,and then, if wraparound occurs, the systemInfoValueTagExt may beincreased by one.

Thereafter, at step S2830, the eNB may broadcast the system information(SIB1) including the updated information (IE).

FIG. 29 illustrates a block configuration of UE according to the presentinvention.

Referring to FIG. 29, the UE may include a radio frequency (RF)processor 2910, a baseband processor 2920, a storage 2930, and acontroller 2940.

The RF processor 2910 may perform a function, such as band conversionand amplification of a signal, for transmitting and receiving the signalthrough a wireless channel. That is, the RF processor 2910 mayup-convert a baseband signal provided from the baseband processor 2920into an RF band signal to transmit the RF band signal through anantenna, and also down-convert an RF band signal received through theantenna into a baseband signal. For example, the RF processor 2910 mayinclude a transmitter filter, a receiver filter, an amplifier, a mixer,an oscillator, a digital to analog converter (DAC), an analog to digitalconverter (ADC), and the like. Although the drawing shows only oneantenna, the UE may have a plurality of antennas. In addition, the RFprocessor 2910 may include a plurality of RF chains. Further, the RFprocessor 2910 may perform beamforming. For the beamforming, the RFprocessor 2910 may adjust the phase and size of signals transmitted andreceived through a plurality of antennas or antenna elements.

The baseband processor 2920 may perform a conversion function between abaseband signal and a bit stream in accordance with a physical layerstandard of the system. For example, in data transmission, the basebandprocessor 2920 may create complex symbols by encoding and modulatingtransmission bit streams. Also, in data reception, the basebandprocessor 2920 may restore reception bit streams by demodulating anddecoding a baseband signal provided from the RF processor 2910. In caseof complying with orthogonal frequency division multiplexing (OFDM)scheme, in data transmission, the baseband processor 2920 may generatecomplex symbols by encoding and modulating transmission bit streams, mapthe complex symbols to subcarriers, and construct OFDM symbols throughan inverse fast Fourier transform (IFFT) operation and a cyclic prefix(CP) insertion. In addition, in data reception, the baseband processor2920 may divide a baseband signal provided from the RF processor 2910into OFDM symbol units, restore signals mapped to subcarriers through afast Fourier transform (FFT) operation, and restore reception bitstreams through demodulation and decoding.

The baseband processor 2920 and the RF processor 2910 may transmit andreceive a signal as described above. Accordingly, the baseband processor2920 and the RF processor 2910 may be referred to as a transmittingunit, a receiving unit, a transceiver, or a communication unit. Inaddition, at least one of the baseband processor 2920 and the RFprocessor 2910 may include a plurality of communication modules tosupport a plurality of different wireless access technologies. Also, atleast one of the baseband processor 2920 and the RF processor 2910 mayinclude different communication modules for processing signals ofdifferent frequency bands. For example, the different wireless accesstechnologies may include a wireless LAN (e.g., IEEE 802.11), a cellularnetwork (e.g., LTE), and the like. In addition, the different frequencybands may include a super high frequency (SHF) band (e.g., 2.5 GHz, 5GHz), and a millimeter wave (e.g., 60 GHz) band.

The storage 2930 may store a basic program for the operation of the UE,an application program, and data such as setting information. Inparticular, the storage 2930 may store information associated with asecond access node that performs wireless communication by using asecond wireless access technology. Also, the storage 2930 may providethe stored data in response to a request of the controller 2940.

The controller 2940 may control overall operations of the UE. Forexample, the controller 2940 may transmit and receive a signal throughthe baseband processor 2920 and the RF processor 2910. Also, thecontroller 2940 writes and read data to and from the storage 2940. Forthis, the controller 2940 may include at least one processor. Forexample, the controller 2940 may include a communication processor (CP)for perform the control for communication and an application processor(AP) for controlling an upper layer such as an application program.According to an embodiment of the present invention, the controller 2940may control the UE to perform the above-described operations andprocedures of the UE.

Specifically, the controller 2940 may acquire system information fromthe eNB.

The controller 2940 that acquires the system information may identifywhether the system information includes the second DRX configurationinformation. Specifically, the controller 2940 may determine whether thesystem information includes the second DRX-related first information andthe paging-related second parameter (the nB′ value).

The controller 2940 may perform an RRC connection establishment process.After the RRC connection is completed, the controller 2940 may transmita request message to the MME. If the UE prefers to apply the second DRX(eDRX) or if the UE supports the second DRX, the controller 2940 mayinclude the first DRX-related second information (the UE specific DRX)and the second DRX-related second information (the UE specific eDRXvalue) in the request message and transmit the request message to theMME.

In addition, the controller 2940 may receive a response messagecorresponding to the request message from the MME.

The controller 2940 that receives the response message may determinewhether the second DRX-related third information (the allowed eDRXparameter) is included in the message. The second DRX-related thirdinformation (the allowed eDRX parameter) may include informationindicating whether the MME supports the second DRX (eDRX), or the secondDRX (eDRX) cycle information having to be applied by the UE.

When the response message includes the second DRX-related thirdinformation, the controller 2940 may perform an RRC connection releaseprocess. The controller 2940 that releases the RRC connection mayoperate by applying the second DRX (eDRX).

For this, the controller 2940 may derive the second DRX cycle (T′) andthe first DRX cycle (T) by using the above-described method, and thendetermine the PHF and the PF. This step may be performed before the RRCconnection release.

In addition, when the calculated PHF arrives, the controller 2940 maysequentially receive the MIB and SIB1.

The controller 2940 that receives the system information may identifythe systemInfoValueTag or systemInfoValueTagExt value included in theSIB1. The controller 2940 may receive the SIB1 at least once every T′,which is the second DRX (eDRX) cycle, and then identify thesystemInfoValueTag or systemInfoValueTagExt. In performing the DRXoperation according to the second DRX (eDRX) cycle, the controller 2940may receive the SIB1 closest to the first PF and PO of the PHFdetermined according to the second DRX (eDRX) cycle in the time domain.Alternatively, the controller 2940 may receive the closest SIB1 amongSIB1s occurring after (or before) the first PF and PO of the PHF.

Thereafter, the controller 2940 may determine whether the identifiedvalue (of the IEs) and the stored value are different from each other.

If there is no difference, the controller 2940 does not need to updatethe system information.

On the other hand, if the stored value differs from the identifiedvalue, the controller 2940 may receive the system information beingcurrently broadcasted by the eNB.

Meanwhile, if the eNB does not broadcast the second DRX-related firstinformation and the paging-related second parameter (nB′), or if the MMEdoes not transmit the second DRX-related third information (the allowedeDRX parameter), the controller 2940 may perform only the first DRX(typical DRX) process.

Meanwhile, the above operation may be similarly applied to the UE whichis in the connected state, and the details are the same as describedabove. Therefore, a description thereof will is omitted hereinafter.

FIG. 30 illustrates a block configuration of eNB according to thepresent invention.

As shown in FIG. 30, the eNB may include an RF processor 3010, abaseband processor 3020, a backhaul communication unit 3030, a storage3040, and a controller 3050.

The RF processor 3010 may perform a function, such as band conversionand amplification of a signal, for transmitting and receiving the signalthrough a wireless channel. That is, the RF processor 3010 mayup-convert a baseband signal provided from the baseband processor 3020into an RF band signal to transmit the RF band signal through anantenna, and also down-convert an RF band signal received through theantenna into a baseband signal. For example, the RF processor 3010 mayinclude a transmitter filter, a receiver filter, an amplifier, a mixer,an oscillator, a DAC, an ADC, and the like. Although the drawing showsonly one antenna, the first access node may have a plurality ofantennas. In addition, the RF processor 3010 may include a plurality ofRF chains. Further, the RF processor 3010 may perform beamforming. Forthe beamforming, the RF processor 3010 may adjust the phase and size ofsignals transmitted and received through a plurality of antennas orantenna elements.

The baseband processor 3020 may perform a conversion function between abaseband signal and a bit stream in accordance with a physical layerstandard of the first wireless access technology. For example, in datatransmission, the baseband processor 3020 may create complex symbols byencoding and modulating transmission bit streams. Also, in datareception, the baseband processor 3020 may restore reception bit streamsby demodulating and decoding a baseband signal provided from the RFprocessor 3010. In case of complying with OFDM scheme, in datatransmission, the baseband processor 3020 may generate complex symbolsby encoding and modulating transmission bit streams, map the complexsymbols to subcarriers, and construct OFDM symbols through an IFFToperation and a CP insertion. In addition, in data reception, thebaseband processor 3020 may divide a baseband signal provided from theRF processor 3010 into OFDM symbol units, restore signals mapped tosubcarriers through an FFT operation, and restore reception bit streamsthrough demodulation and decoding. The baseband processor 3020 and theRF processor 3010 may transmit and receive a signal as described above.Thus, the baseband processor 3020 and the RF processor 3010 may bereferred to as a transmitting unit, a receiving unit, a transceiver, acommunication unit, or a wireless communication unit.

The backhaul communication unit 3030 may provide an interface forperforming communication with other node in the network. That is, thebackhaul communication unit 3030 may convert a bit stream transmittedfrom the main eNB to another node, e.g., a sub-eNB, a core network,etc., into a physical signal, and may also convert a physical signalreceived from such other node into a bit stream.

The storage 3040 may store a basic program for the operation of the maineNB, an application program, and data such as setting information. Inparticular, the storage 3040 may store information on a bearer allocatedto connected UE, a measurement result reported from the connected UE,and the like. In addition, the storage 3040 may store information fordetermining whether to provide or suspend multiple connections to orfrom the UE. Also, the storage 3040 may provide the stored data inresponse to a request of the controller 3050.

The controller 3050 may control overall operations of the main eNB. Forexample, the controller 3050 may transmit and receive a signal throughthe baseband processor 3020 and the RF processor 3010 or through thebackhaul communication unit 3030. Also, the controller 3050 writes andread data to and from the storage 3040. For this, the controller 3050may include at least one processor. According to an embodiment of thepresent invention, the controller 3050 may include a multi-connectioncontroller 3052 for performing control for providing multipleconnections to the UE. For example, the controller 3050 may control theeNB to perform the above-described operations and procedures.

Specifically, the controller 3050 may determine whether systeminformation is updated.

If the system information is updated, the controller 3050 may increasesystemInfoValueTag and systemInfoValueTagExt by one. Alternatively, thevalue of systemInfoValueTag may be increased by one, and then, ifwraparound occurs, the systemInfoValueTagExt may be increased by one.

Thereafter, the controller 3050 may broadcast the system information(SIB1) including the updated information (IE).

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it is clearlyunderstood that the same is by way of illustration and example only andis not to be taken in conjunction with the present invention. It will beunderstood by those skilled in the art that various changes in form anddetails may be made therein without departing from the subject matterand scope of the present invention.

What is claimed is:
 1. A method performed by a terminal in a wirelesscommunication system, the method comprising: receiving, from a basestation, first system information including information indicating thatan extended discontinuous reception (DRX) mode is allowed in a cellassociated with the base station; transmitting, to an entity formanaging mobility of the terminal, a request message including firstinformation on a first DRX cycle for an operation in the extended DRXmode to enable the extended DRX mode; receiving, from the entity, aresponse message based on the request message; identifying whether theresponse message includes second information on a second DRX cycle forthe operation in the extended DRX mode; performing the operation in theextended DRX mode based on the second information, in case that theresponse message includes the second information; and performing anoperation in a regular DRX mode based on third information on a defaultcycle, in case that the response message does not include the secondinformation.
 2. The method of claim 1, further comprising receiving,from the base station, second system information including the thirdinformation on the default cycle.
 3. The method of claim 1, furthercomprising determining whether to request enablement of the extended DRXmode, wherein the request message includes the first information, incase that it is determined to request the enablement of the extended DRXmode.
 4. A method performed by a base station in a wirelesscommunication system; the method comprising: transmitting, to aterminal, first system information including information indicating thatan extended discontinuous reception (DRX) mode is allowed in a cellassociated with the base station; receiving, from an entity for managingmobility of the terminal, a paging message; performing an operation inthe extended DRX mode based on first information on a first DRX cyclefor the operation in the extended DRX mode, in case that the pagingmessage includes the first information; and performing an operation in aregular DRX mode based on second information on a default cycle, in casethat the paging message does not include the first information.
 5. Themethod of claim 4, further comprising transmitting, to the terminal,second system information including the second information on thedefault cycle.
 6. A method performed by an entity for managing mobilityof the terminal in a wireless communication system, the methodcomprising: receiving, from a terminal, a request message includingfirst information on a first discontinuous reception (DRX) cycle for anoperation in an extended DRX mode to enable the extended DRX mode;determining whether to accept use of the extended DRX mode based on therequest message; transmitting, to the terminal, a response messageincluding second information on a second DRX cycle for the operation inthe extended DRX mode, in case that the use of the extended DRX mode isaccepted; and transmitting, to the terminal, a response message notincluding the second information, in case that the use of the extendedDRX mode is rejected wherein the request message is generated based onfirst system information including information indicating that theextended DRX mode is allowed in a cell associated with a base station,wherein a paging message transmitted to the base station includes thesecond information in case that the use of the extended DRX mode isaccepted, and wherein the paging message does not include the secondinformation in case that the use of the extended DRX mode is rejected.7. A terminal in a wireless communication system, the terminalcomprising: a transceiver; and a controller configured to: receive, viathe transceiver, from a base station, first system information includinginformation indicating that an extended discontinuous reception (DRX)mode is allowed in a cell associated with the base station, transmit,via the transceiver, to an entity for managing mobility of the terminal,a request message including first information on a first DRX cycle foran operation in the extended DRX mode to enable the extended DRX mode,receive, via the transceiver, from the entity, a response message basedon the request message, identify whether the response message includessecond information on a second DRX cycle for the operation in theextended DRX mode, perform the operation in the extended DRX mode basedon the second information, in case that the response message includesthe second information, and perform an operation in a regular DRX modebased on third information on a default cycle, in case that the responsemessage does not include the second information.
 8. The terminal ofclaim 7, wherein the controller is further configured to receive, viathe transceiver, from the base station, second system informationincluding the third information on the default cycle.
 9. The terminal ofclaim 7, wherein the controller is further configured to determinewhether to request enablement of the extended DRX mode, and wherein therequest message includes the first information, in case that it isdetermined to request the enablement of the extended DRX mode.
 10. Abase station in a wireless communication system, the base stationcomprising: a transceiver; and a controller configured to: transmit, viathe transceiver, to a terminal, first system information includinginformation indicating that an extended discontinuous reception (DRX)mode is allowed in a cell associated with the base station, receive, viathe transceiver, from an entity for managing mobility of the terminal, apaging message, perform an operation in the extended DRX mode based onfirst information on a first DRX cycle for the operation in the extendedDRX mode, in case that the paging message includes the firstinformation, and perform an operation in a regular DRX mode based onsecond information on a default cycle, in case that the paging messagedoes not include the first information.
 11. The base station of claim10, wherein the controller is further configured to transmit, via thetransceiver, to the terminal, second system information including thesecond information on the default cycle.
 12. An entity for managingmobility of a terminal in a wireless communication system, the entitycomprising: a transceiver; and a controller configured to: receive, viathe transceiver, from the terminal, a request message including firstinformation on a first discontinuous reception (DRX) cycle for anoperation in an extended DRX mode to enable the extended DRX mode,determine whether to accept use of the extended DRX mode based on therequest message, transmit, via the transceiver, to the terminal, aresponse message including second information on a second DRX cycle forthe operation in the extended DRX mode, in case that the use of theextended DRX mode is accepted, and transmit, via the transceiver, to theterminal, a response message not including the second information, incase that the use of the extended DRX mode is rejected wherein therequest message is generated based on first system information includinginformation indicating that the extended DRX mode is allowed in a cellassociated with a base station, wherein a paging message transmitted tothe base station includes the second information in case that the use ofthe extended DRX mode is accepted, and wherein the paging message doesnot include the second information in case that the use of the extendedDRX mode is rejected.